Effect of a monetary incentive on response to a mail survey. Increasing response rates in a survey of Medicaid enrollees: the effect of a prepaid monetary incentive and mixed modes (mail and telephone). A randomized trial of incentives to improve response rates to a mailed women's health questionnaire. Timing of patient satisfaction assessment: effect on questionnaire acceptability, completeness of data, reliability and variability of scores. Mailed survey follow-ups--are postcard reminders more cost-effective than second questionnaires? Design, objectives, and lessons from a pilot 25 year follow up re-survey of survivors in the Whitehall study of London Civil Servants. A randomized trial of opinion leader endorsement in a survey of orthopaedic surgeons: effect on primary response rates. Day-of-the-week effect on doctors' response to a postal questionnaire. Effects on subject response of information brochures and small cash incentives in a mail-based case-control study. Physician response rates to a mail survey by specialty and timing of incentive. Scratch lottery tickets are a poor incentive to respond to mailed questionnaires. Response rate to mailed epidemiologic questionnaires: a population-based randomized trial of variations in design and mailing routines. A randomised controlled trial to assess the effectiveness of offering study results as an incentive to increase response rates to postal questionnaires [ISRCTN26118436]. Increasing returns of physician surveys. Does anonymity increase response rate in postal questionnaire surveys about sensitive subjects? A randomised trial. Recruiting survey respondents to mailed surveys: controlled trials of incentives and prompts. Response rates of Victorian general practitioners to a mailed survey on miscarriage: randomised trial of a prize and two forms of introduction to the research. Effect of a monetary incentive on chiropractors' response rate and time to respond to a mail survey. A comparison of response rate and time according to the survey methods used: a randomized controlled trial. Recruiting patients to medical research: double blind randomised trial of "opt-in" versus "opt-out" strategies. The effect of cash and other financial inducements on the response rate of general practitioners in a national postal study. Maximising response rates in a survey of general practitioners. Lessons from a Victorian survey on sexually transmissible diseases. Effect on survey return rates of having a signed or unsigned postcard as the third-wave mailing. In a mailed physician survey, questionnaire length had a threshold effect on response rate. Effects of different monetary incentives on the return rate of a national mail survey of physicians. Response rate according to title and length of questionnaire. Types of advance notification in reminder letters and response rates. Printed signatures and response rates. Increasing response rates for mailed surveys of Medicaid clients and other low-income populations. Response rates to surveys with self-addressed, stamped envelopes versus a self-addressed label. Labour-saving strategies to maintain survey response rates: a randomised trial. Unexpected effects of a prior feedback letter and a professional layout on the response rate to a mail survey in Geneva. Collecting saliva samples by mail. Differential effectiveness of telephone prompts by medical and nonmedical staff in increasing survey response rates: a randomised trial. From the generic to the condition-specific?: Instrument order effects in Quality of Life Assessment. The cost effectiveness of including pencils and erasers with self-completion epidemiological questionnaires. Controlled trial of the effect of length, incentives, and follow-up techniques on response to a mailed questionnaire. Unexpected mailed survey response rates. Identifying a sample of elderly people by a postal screen. Some experiments with factors that might affect the response of mothers to a postal questionnaire. The effectiveness of an advance notice letter on the recruitment of African Americans and Whites for a mailed patient satisfaction survey. The effects of cash and lottery incentives on mailed surveys to physicians: a randomized trial. Increasing response rates to postal questionnaires: a randomised trial of variations in design. Dentists' response to financial incentives in a mail survey of malpractice liability experience. Effectiveness of monetary incentives for recruiting adolescents to an intervention trial to reduce smoking. Effect of handwritten, hand-stamped envelopes on response rate in a followup study of hip replacement patients. Enclosing a pen with a postal questionnaire can significantly increase the response rate. Combining conditional and unconditional recruitment incentives could facilitate telephone tracing in surveys of postpartum women. Response rates with different distribution methods and reward, and reproducibility of a quantitative food frequency questionnaire. Survey response rates to a professional association mail questionnaire. Impact of a postcard versus a questionnaire as a first reminder in a postal lifestyle survey. A randomized trial of direct mailing of fecal occult blood tests to increase colorectal cancer screening. Race-specific versus general stamps on African-American women's survey return rates. Cost effectiveness of a prize draw on response to a postal questionnaire: results of a randomised trial among orthopaedic outpatients in Edinburgh. Thicker paper and larger font increased response and completeness in a postal survey. A study of mail survey method. Effects of disseminating research findings on response rates in a community survey: a randomised controlled trial. Provision of pen along with questionnaire does not increase the response rate to a postal survey: a randomised controlled trial. A randomised trial of telephone versus postcard prompts to enhance response rate in a phased population-based study about community preferences. Response rates to a mailed survey targeting childhood cancer survivors: a comparison of conditional versus unconditional incentives. Primer postcard improves postal survey response rates. The use of a prepaid incentive to convert nonresponders on a survey of physicians. Improving response rates among doctors: randomised trial. Effects of different designs and extension of a food frequency questionnaire on response rate, completeness of data and food frequency responses. In a randomized study of envelope and ink color, colored ink was found to increase the response rate to a postal questionnaire. Survey return rates using a covering letter signed by a graduate student or faculty member. Eliciting survey cooperation: incentives, self-interest, and norms of cooperation. The impact of different response alternatives on responders' reporting of health-related behaviour in a postal survey. Factors impacting questionnaire response in a Dutch retrospective cohort study. Increasing response to mailed questionnaires by including a pencil/pen. The effect of a direct payment or a lottery on questionnaire response rates: a randomised controlled trial. A randomised controlled trial to determine the effect on response of including a lottery incentive in health surveys [ISRCTN32203485]. Effect on survey response rate of hand written versus printed signature on a covering letter: randomised controlled trial [ISRCTN67566265]. Cross validation of some psychometric properties of the CSQ and its differential return rate as a function of token financial incentive. Improving return rates for health-care outcome. Telephone reminders are a cost effective way to improve responses in postal health surveys. Initial nonresponders had an increased response rate after repeated questionnaire mailings. Randomized trial of use of a monetary incentive and a reminder card to increase the response rate to a mailed health survey. The effects of variations in mode of delivery and monetary incentive on physicians' responses to a mailed survey assessing STD practice patterns. The effects of lottery incentive and length of questionnaire on health survey response rates: a randomized study. The effect of two mailing strategies on the response to a survey of physicians. Response to mail surveys: effect of a request to explain refusal to participate. The ARIC Study Investigators. A useless raffle. Incentives increased return rates but did not influence partial nonresponse or treatment outcome in a randomized trial. Possible factors affecting response to postal questionnaires: findings from a study of general practitioner services. The end-of-study patient survey: methods influencing response rate in the AVID Trial. Print format and sender recognition were related to survey completion rate. Effect of a newspaper article on the response to a postal questionnaire. Does questionnaire structure influence response in postal surveys? Do sexual health questions alter the public's response to lifestyle questionnaires? Effect of timing on the response to postal questionnaires concerning satisfaction with anaesthesia care. Maximizing response rates to a survey of dentists: a randomized trial. Does requesting sensitive information on postal questionnaires have an impact on response rates? A randomised controlled trial in the south west of England. Properties of the Picker Patient Experience questionnaire in a randomized controlled trial of long versus short form survey instruments. Effects of characteristics of the survey instrument on response rates to a mail survey of community hospitals. No difference in response rate to a mailed survey among prostate cancer survivors using conditional versus unconditional incentives. A randomized trial of the impact of certified mail on response rate to a physician survey, and a cost-effectiveness analysis. The effect on response rates of offering a small incentive with a mailed questionnaire. Effectiveness of various mailing strategies among nonrespondents in a prospective cohort study. Questionnaire color and response rates to mailed surveys. A randomized trial and a meta-analysis. The use of monetary incentives in a community survey: impact on response rates, data quality, and cost. Randomized trial of financial incentives and delivery methods for improving response to a mailed questionnaire. Effect of mailed reminders on the response rate in surveys among patients in general practice. Do income questions and seeking consent to link medical records reduce survey response rates? A randomised controlled trial among older people. [Response rates and non-response bias in a health-related mailed survey]. Recruiting blacks to the Adventist health study: Do follow-up phone calls increase response rates? Improving the assessment of (in)patients' satisfaction with hospital care. A mail survey of United States hematologists and oncologists: a comparison of business reply versus stamped return envelopes. Comparison of responses to a US 2 dollar bill versus a chance to win 250 US dollars in a mail survey of emergency physicians. Screening optometric patients by questionnaire: methods of improving response. Short report: encouraging GPs to complete postal questionnaires--one big prize or many small prizes? A randomized controlled trial. An informational versus monetary incentive in increasing physicians' response rates. Questionnaire order significantly increased response to a postal survey sent to primary care physicians. Obtaining DNA from a geographically dispersed cohort of current and former smokers: use of mail-based mouthwash collection and monetary incentives. Response rates and representativeness: a lottery incentive improves physician survey return rates. Does it pay to pay? A randomized trial of prepaid financial incentives and lottery incentives in surveys of nonphysician healthcare professionals. [Mail questionnaires. A useful strategy for the follow-up of patients with a cerebrovascular stroke?]. The effect of a monetary incentive on return of a postal health and development questionnaire: a randomised trial [ISRCTN53994660]. Survey return rates as a function of priority versus first-class mailing. Physician participation in research surveys. A randomized study of inducements to return mailed research questionnaires. Timing payments to subjects of mail surveys: cost-effectiveness and bias. Effects of mailing strategies on response rate, response time, and cost in a questionnaire study among nurses. Improving response rates through incentive and follow-up: the effect on a survey of physicians' knowledge of genetics. Longer response scales improved the acceptability and performance of the Nottingham Health Profile. A comparison of response rate, data quality, and cost in the collection of data on sexual history and personal behaviors. Mail survey approaches and in-person interview. Prepayment was superior to postpayment cash incentives in a randomized postal survey among physicians. Using a diary to record near misses and minor injuries--which method of administration is best? Comparison of open and closed questionnaire formats in obtaining demographic information from Canadian general internists. Chance of free dinner increases response to mail questionnaire. Increasing response rates in physicians' mail surveys: an experimental study. [Evaluation of inpatient satisfaction. Comparison of different survey methods]. Randomized trial of 5 dollars versus 10 dollars monetary incentives, envelope size, and candy to increase physician response rates to mailed questionnaires. The effect of conducting a lottery on questionnaire response rates: a randomised controlled trial. No increase in response rate by adding a web response option to a postal population survey: a randomized trial. Do postage stamps versus pre-paid envelopes increase responses to patient mail surveys? A randomised controlled trial. Selected questionnaire size and color combinations were significantly related to mailed survey response rates. Do postage-stamps increase response rates to postal surveys? A randomized controlled trial. Increasing response to a postal survey of sedentary patients - a randomised controlled trial [ISRCTN45665423]. Improving the measurement of quality of life in older people: the York SF-12. A monetary incentive increases postal survey response rates for pharmacists. Effect of prize draw incentive on the response rate to a postal survey of obstetricians and gynaecologists: a randomised controlled trial. [ISRCTN32823119]. Conducting physician mail surveys on a limited budget. A randomized trial comparing $2 bill versus $5 bill incentives. Use of a coded postcard to maintain anonymity in a highly sensitive mail survey: cost, response rates, and bias. Will donations to their learned college increase surgeons' participation in surveys? A randomized trial. Does a deadline improve men's participation in self-administered health surveys? A randomized controlled trial in general practice. What can you ask about? The effect on response to a postal screen of asking about two potentially sensitive questions. Is shorter always better? Relative importance of questionnaire length and cognitive ease on response rates and data quality for two dietary questionnaires. Effects of incentive size and timing on response rates to a follow-up wave of a longitudinal mailed survey. A randomized trial of the impact of telephone and recorded delivery reminders on the response rate to research questionnaires. Does sponsorship matter in patient satisfaction surveys? A randomized trial. Increasing the response rate to a mailed questionnaire by including more stamps on the return envelope: a cotwin control study. Effect of paper quality on the response rate to a postal survey: a randomised controlled trial. ISRCTN 32032031.
We assessed the effect of a $1 incentive on response to a two-page questionnaire which was sent to 8356 female cosmetologists between 22 and 36 years old. The study population was randomly assigned to one of three groups in which a $1 incentive was enclosed with either the first or second mailing, or with none of the mailings. Ten percent of questionnaires were returned by the postal service because of an incorrect address or death of the addressee and were omitted from response calculations. Of the remaining questionnaires, 79% were completed and returned after up to three mailings. The cumulative response was highest among cosmetologists who received a $1 incentive with the first mailing, (81%; 95% confidence interval (CI), 80 to 82), intermediate among those who received $1 with the second mailing (78%, 95% CI, 77 to 79), and lowest among cosmetologists who received no incentive (74%; 95% CI, 70 to 78). Characteristics of cosmetologists who responded after having received a "41 incentive were similar to those who responded without having received an incentive. The higher costs per response incurred by the use of an incentive must be weighed against the benefit of higher response. We sought to evaluate the effect of pairing a mixed-mode mail and telephone methodology with a prepaid US 2.00 dollars cash incentive on response rates in a survey of Medicaid enrollees stratified by race and ethnicity.
                Sampling was conducted in 2 stages. The first stage consisted of a simple random sample (SRS) of Medicaid enrollees. In the second stage, American Indian, African American, Latino, Hmong, and Somali enrollees were randomly sampled. A total of 8412 enrollees were assigned randomly to receive a mail survey with no incentive or a US 2.00 dollars bill.
                The response rate within the SRS after the mail portion was 54% in the incentive group and 45% in the nonincentive group. Response rates increased considerably with telephone follow-ups. The incentive SRS response rate increased to 69%, and the nonincentive response rate increased to 64%. Differences between incentive conditions are more pronounced after the first mailing (P < 0.01); almost all differences remained significant (P < 0.05) after the completion of the mail mode. The inclusion of the US 2.00 dollars incentive had similar effects on response rates and cost across the different racial and ethnic strata, except for Latino enrollees.
                A mixed-mode mail and telephone methodology is effective for increasing response rates in a Medicaid population overall and within different racial and ethnic groupings. The effectiveness of this strategy can be enhanced, in terms of response rate and cost, by including a US 2.00 dollars prepaid incentive. Mailed questionnaires can be a convenient method for collecting data on women's health, although poor response rates are a concern.
                As part of a survey of women's health conducted in Maryland in 2001, a randomized trial was performed to assess the effects of two incentives (US dollars 1.00 or a lottery ticket) as well as precontact with an introductory postcard on response rates. Questionnaires were mailed to 3000 women aged 40-60 who were randomized to one of six incentive/precontact groups: lottery/postcard, money/postcard, postcard only, lottery only, money only, or no incentive/no postcard.
                The overall response rate was 37.6%. Each incentive/precontact group yielded a higher response rate than the no incentive/no postcard group, although only the response rates for the lottery/postcard group (41.3%) and the money only group (40.0%) were significantly higher than that of the no incentive/no postcard group (33.1%). Money was the only factor that had a significant independent effect on likelihood of response (hazards ratio [HR] compared to no incentive = 1.22, 95% confidence interval [CI] = 1.03, 1.43). Response rates were lower in minority ZIP codes, although the effects of the incentives were generally greater than in the nonminority ZIP codes.
                These results indicate that response rates to mailed women's health questionnaires may be improved with modest incentives, particularly cash incentives. The present study compared the performance of a multidimensional patient satisfaction questionnaire according to the timing of questionnaire administration. Comparisons were made in terms of: (a) the completeness and representativeness of the data set (number of missing questionnaires, number missing item responses, respondents' representativeness to the target population); (b) the questionnaire acceptability to respondents (time and difficulty to complete); (c) the questionnaire reliability; and (d) variability of scores. One hundred and ten consecutive breast cancer patients hospitalised for surgery were randomised between being sent the comprehensive assessment of satisfaction with care (CASC) at 2 weeks (T(2W)) or at 3 months (T(3M)) after hospital discharge. The time to complete the CASC was shorter at T(3M) than at T(2W) and the mean percentage of item omission was lower at T(3M) (1.68) than at T(2W) (3.82). However, the response rate was much higher at T(2W) (87%) than at T(3M) (66%), making item omission non-significant. At both times of questionnaire administration samples were equally biased towards patients having undergone a less invasive surgery. Moreover, the multi-item scales of the CASC demonstrated adequate internal consistency coefficients, except the general satisfaction scale at T(3M), and fairly symmetrical distribution of scores. Response rate should be considered in priority. This criteria favoured an administration of the CASC shortly after discharge. Besides in a cancer patient population care experience and perception may vary in a 6 weeks time lapse. The timing of assessment needs to be clearly specified in cancer patients satisfaction survey. Finding cost-effective ways to increase response to mailed surveys is a concern for many nurse researchers. This study compared two follow-up methods: sending a second questionnaire packet versus sending a reminder postcard to those who did not respond to an initial mailing. Although the second questionnaire yielded a higher response than did the postcard, the cost per additional response was approximately 2 1/2 times higher for the questionnaire than for the postcard when the differential cost of the two mailings is considered. To assess the feasibility of conducting a re-survey of men who are resident in the United Kingdom 25 years after enrollment in the Whitehall study of London Civil Servants.
                A random sample of 401 study survivors resident in three health authority areas was selected for this pilot study. They were mailed a request to complete a self administered questionnaire, and then asked to attend their general practice to have their blood pressure, weight, and height measured and a blood sample collected into a supplied vacutainer, and mailed to a central laboratory. Using a 2 x 2 factorial design, the impact of including additional questions on income and of an informant questionnaire on cognitive function was assessed.
                Accurate addresses were obtained from the health authorities for 96% of the sample. Questionnaires were received from 73% and blood samples from 61% of the sample. Questions on income had no adverse effect on the response rate, but inclusion of the informant questionnaire did. Between 1970 and 1995 there were substantial changes within men in the mean blood pressure and blood total cholesterol recorded, as reflected by correlation coefficients between 1970 and 1995 values of 0.26, and 0.30 for systolic and diastolic blood pressure and 0.38 for total cholesterol.
                This pilot study demonstrated the feasibility of conducting a re-survey using postal questionnaires and mailed whole blood samples. The magnitude of change in blood pressure and blood total cholesterol concentrations within individuals was greater than anticipated, suggesting that such remeasurements may be required at different intervals in prospective studies to help interpret risks associations properly. These issues will be considered in a re-survey of the remaining survivors of the Whitehall study. Opinion leaders have been shown to have significant influence on the practice of health professionals and patient outcomes.
                Using focus groups, key informants, and sampling to redundancy techniques, we developed a questionnaire of surgeons' preferences in the treatment of tibial shaft fractures. Twenty-two well-respected and widely known orthopaedic traumatologists endorsed the questionnaire. We randomized 395 surgeon members of the Orthopaedic Trauma Association to receive either a questionnaire that included a letter informing them of the opinion leaders' endorsement, or a questionnaire without the endorsement.
                Surgeons who received the letter of endorsement had a significantly lower response rate at 2, 4, and 8 weeks. The absolute difference in response rates was 7.8% (4.6% versus 12.4%, P < 0.05) at 2 weeks, 13.1% at 4 weeks (28.6% versus 41.7% P < 0.02), and 12.3% at 8 weeks (47.5% versus 59.8% P = 0.02).
                The addition of a letter listing expert surgeons who endorse the survey lead to significantly lower primary response rates. Those interested in influencing physician responses cannot always assume a positive effect from endorsement by opinion leaders To test a possible day-of-the-week effect on doctors' response rate to a postal questionnaire.
                Dispatch of postal questionnaire randomized to Thursday or Saturday.
                A nationwide survey on doctors' attitudes.
                200 general practitioners and 260 practising specialists/consultants.
                Response rate and Kaplan-Meier survival curve for no-response.
                The probability of response was not influenced by receiving the questionnaire just before or just after a week-end.
                Response rates in postal surveys sent to doctors cannot be improved by their receiving the questionnaire just before a week-end. To investigate the impact on subject response of an information brochure and cash incentives included with mailed questionnaires in case-control studies.
                A randomized trial was carried out within a case-control study investigating cancer in the Province of Ontario. Brochures were included with half of the mailed questionnaires sent to 7487 cases and 2561 controls. Controls were also sent cash incentives of $2, $5, or no money.
                With the brochure, response changed from 75.0% to 75.8% in cases, and from 70.3% to 71.1% in controls. Adjusting for differences in age, residence, sex, and cancer site/status, the change was 0.2% [95% confidence interval (CI) = -1.7-2.1] in cases, and 0.6% (95% CI = -3.1-4.3) in controls. The $2 and $5 incentives increased overall response in controls from 61.9% to 72.8% and 77.2%, respectively, i.e., by 10.9% (95% CI = 6.1-15.6) and 15.1% (95% CI = 10.4-19.7), after adjustment. This effect was largely confined to urban areas (for $2 and $5, respectively: 5.5% and 14.2% in Toronto, 15.3% and 20.4% in other urban areas vs. 2.7% and 1.0% in rural areas; p = 0.02). Response time showed little or no improvement when the brochure was included, but was markedly reduced for both the $2 and $5 incentives.
                Cash incentives can improve subject response in epidemiologic studies, whereas information brochures do not appear to have an effect. Historically, achieving a high response rate on physician surveys has been a challenging task. Given such concerns, understanding research strategies that facilitate adequate response rates is important. Primary care physician responses to a mail survey on smoking cessation are summarized by physician specialty and timing of incentive.
                A stratified random-sample design, stratified by patient populations-adults, adolescents, and pregnant women-was used. The sampling frame included New Jersey internists, general practitioners, family physicians, pediatricians, and obstetrician-gynecologists. A total of 2100 physicians, 700 physicians from each patient strata, were sampled and mailed a smoking-cessation survey in summer 2002. The sample was randomized by incentive timing: Half received the incentive (i.e., 25 dollars gift card) with the first survey mailing, and half received the incentive on receipt of their completed survey.
                The promised-incentive group achieved a significantly lower response rate (56%) compared with the up-front-incentive group (71.5%). Response rates by medical specialty varied overall and within incentive groups. The difference between the incentive groups was greatest among obstetrician-gynecologists (i.e., 20.2 percentage points) and was least among pediatricians (i.e., 5.8 percentage points).
                Physician response rates to mail surveys are greatly improved, especially among certain medical specialties, by using up-front incentives. It has been demonstrated that the enclosure of money with a mailed questionnaire increases the response rate significantly. We evaluated scratch lottery tickets as an alternative to cash.
                1500 randomly selected Norwegians between the ages of 40 and 65 years were sent a short questionnaire. 250 received one lottery scratch ticket worth 20 Norwegian kroner (approximately 3 USD) together with the questionnaire, 250 received two scratch tickets, and 250 were promised two scratch tickets if they replied within one week. A fourth group of 250 persons received a 50 kroner banknote with the questionnaire. The remaining 500 letters served as controls.
                The overall response rate after 6 weeks was 77%. Logistic regression analysis showed that only the 50 kroner group had a response rate that was statistically significantly higher than the controls (p < 0.0001). It was also significantly higher than that in any of the other incentive groups (p < 0.0001, p < 0.004 and p < 0.0001 respectively). Female sex (p < 0.001) and age (p < 0.002) increased the response rate significantly.
                It is possible that the recipients scratched their cards before completing the questionnaire, and that it was a disincentive for the majority that they did not win anything. Lottery scratch tickets are no substitute for cash as an incentive to respond to a questionnaire. Although self-administered questionnaires are major sources of information in epidemiology, comparatively little has been done to study practical aspects of design and mailing. The objective of this study was to evaluate various measures taken to increase the response rate. A questionnaire was mailed in July 1995 to a random sample (n = 2,000) of the Swedish population aged 20-79 years. Using a randomized factorial study design, the questionnaire and mailing procedures were changed in three ways: preliminary notification, length of the questionnaire, and mention of telephone contact. The overall questionnaire retrieval rate was 49%. Preliminary notification (adjusted odds ratio of receiving a completed questionnaire = 1.30, 95% confidence interval (CI) 1.08-1.56 relative to the absence of preliminary notification) and short length of the questionnaire (odds ratio = 1.24, 95% CI 1.04-1.48 relative to a long questionnaire) were both independently associated with a higher retrieval rate. Of eight possible combinations, the one comprising preliminary notification, a short questionnaire, and no mention of telephone contact gave the highest retrieval rate, 56%. The lowest retrieval rate, 40%, was observed for the combination of no preliminary notification, a long questionnaire, and mention of telephone contact. Young age, male sex, and urban residence significantly lowered the retrieval rate. Although there was a positive association between the questionnaire retrieval rate and partial nonresponse (missing answers in retrieved questionnaires), the marginal losses due to the latter did not cancel the gains by optimized mailing routines. Old age was the strongest determinant of partial nonresponse. The data provide evidence that design and mailing strategies, as well as demographic characteristics, may greatly influence the response rate of mailed epidemiologic questionnaires. Postal questionnaires are widely used to collect outcome data on participants. However, a poor response to questionnaires will reduce the statistical power of the study and may introduce bias. A meta analysis of ten trials offering study results, largely in the fields of education and marketing, was shown to be ineffective, with the odds ratio for response with offering research findings is 0.92 (95% CI 0.75 to 1.11). However uncertainty still exists as it is uncertain whether results from such trials can be extrapolated to that of a health care setting. The aim of this study was to assess whether offering participants study results increases the response rates to postal questionnaires.
                1038 women aged over 70 years were remotely randomised by computer in a 3:1 ratio. 250 participants did not receive the offer of knowing the results of the trial and 788 participants were offered the results of the trial in a postal questionnaire. The main outcome measure was response rate. Chi square test was used to evaluate the overall differences in response rate between the two groups. An adjusted analysis, adjusting for whether the participant was taking calcium and age was also undertaken.
                The response rates were not significantly different Odds Ratio 0.88 (95% confidence intervals 0.48 to 1.63) p = 0.69.
                Offering study results to women living in the community aged over 70 does not increase response rates to postal questionnaires. Although researchers have an ethical obligation to offer participants study results, since 10% of women did not wish to receive the results, investigators should give participants the option to opt out of receiving the study's results. nan The aim of the study was to determine whether complete anonymity improves the response rates to a postal questionnaire.
                The study derived from a series of postal surveys on AIDS knowledge conducted on six different dates in 1986 and 1987. The sample was randomly divided into two, each group being sent the same questionnaire. One group was informed that the replies were anonymous, the other that they were not. The latter were sent reminders.
                Recipients of the questionnaires were drawn from the Southampton electoral rolls.
                300 people in each survey (total 1800) were sent questionnaires, representing on each occasion a different 1:500 systematic sample.
                Response rate was 49% for the anonymous questionnaires and 51% for the numbered questionnaires. Reminders boosted the response in the numbered group to 72%.
                There is no evidence that anonymity improves response to postal questionnaires, but the use of reminders may do so. Three controlled experiments tested the efficacy of 1) a postcard or telephone prompt, 2) a lottery, 3) monetary incentives, and 4) questionnaire length to recruit adult survey respondents to a random sample of residences in San Diego, California, during 1986-1988. In experiment 1, the group randomly assigned to receive a telephone call prenotification plus the lottery incentive responded 26-66% more frequently than did controls (p = 0.02) after a single mailing. The postcard plus lottery was 17-54% more effective than no intervention with controls (p = 0.05). A second mailing of the survey weakened these effects. In experiment 2, the group randomly assigned to receive a two-page survey with the lottery announcement responded 69% more frequently after one mailing (p = 0.03) and 53% more frequently after a second mailing (p = 0.04) than the group that received an eight-page survey without the lottery incentive. The shorter form alone or the lottery alone did not increase response rates significantly relative to the long form without a lottery. In experiment 3, a monetary incentive of $5.00 contingent on response to the second mailing of the survey increased the rate of response from initial "nonresponders" by 100% relative to control who received no incentive (p = 0.03) and 75% over those who received $1.00 not contingent on response (p = 0.04). Little sampling bias and no reactivity was attributable to the recruitment procedures. To identify whether the form of introduction to a study and knowledge of a substantial prize influence the response rate of general practitioners (GPs) to a postal survey.
                A postal survey of 700 randomly selected Victorian GPs concerning management of early pregnancy bleeding and miscarriage, incorporating two randomised-controlled trials of recruitment methods; analysis of response rates and costs at 4 weeks and 11 weeks.
                The response rate was 61.5% of eligible participants. Doctors made aware of a prize were more likely to respond in the first four weeks (difference in response rate 10.2%, 95% confidence interval (CI) 2.8%-17.6%). This difference diminished after the first four weeks. Doctors introduced to the survey by a telephone call were no more likely to respond than those introduced by a postcard. The use of a postcard saved 73% of the cost of introducing the survey by telephone. Female doctors were more likely than males to reply (difference 12.3%, 95% CI 4.7%-19.9%). Rural doctors were no more likely to reply than urban doctors. Very few doctors (16.2%) completed a Practice Assessment activity associated with the survey.
                A valuable prize will accelerate response to a survey by GPs, thereby reducing the costs of follow-up. The cost of telephoned introductions is not justified, when compared with a brief written introduction. nan The purpose of this study was to evaluate the effects of recorded and standard deliveries, and stamped and franked return envelops in a postal survey of Korean-Vietnam veterans. Nine hundred veterans were randomly divided into four subgroups. A randomized controlled trial was conducted for two mailing strategies. The 52 study subjects to whom mail was undeliverable and 36 additional study subjects found not to be residing at the listed addresses were excluded from the study. The 699 (86%) surveys were returned within 39 business days after the first mailing. The response rate for the recorded delivery (88%) was significantly higher than that of the standard delivery (82%)(p = 0.03), and the response rate of the stamped return envelops (88%) was higher than that of the franked return envelops (85%)(p = 0.27). The replies for the recorded and standard deliveries arrived an average of 10.2 and 9.9 business days, respectively, after the first mailing (p = 0.60). The average times of the responses for the stamped and franked return envelops were 9.8 and 10.4 business days, respectively (p = 0.25). Recorded deliveries significantly increased the response rate compared to standard deliveries, and stamped return envelops slightly increased the response rate a little compared to franked return envelops. The timing of response of recorded deliveries was similar to that of standard deliveries but the volume of response of recorded deliveries was higher than that of standard deliveries. To evaluate the effect of opt-in compared with opt-out recruitment strategies on response rate and selection bias.
                Double blind randomised controlled trial.
                Two general practices in England.
                510 patients with angina.
                Patients were randomly allocated to an opt-in (asked to actively signal willingness to participate in research) or opt-out (contacted repeatedly unless they signalled unwillingness to participate) approach for recruitment to an observational prognostic study of patients with angina.
                Recruitment rate and clinical characteristics of patients.
                The recruitment rate, defined by clinic attendance, was 38% (96/252) in the opt-in arm and 50% (128/258) in the opt-out arm (P = 0.014). Once an appointment had been made, non-attendance at the clinic was similar (20% opt-in arm v 17% opt-out arm; P = 0.86). Patients in the opt-in arm had fewer risk factors (44% v 60%; P = 0.053), less treatment for angina (69% v 82%; P = 0.010), and less functional impairment (9% v 20%; P = 0.023) than patients in the opt-out arm.
                The opt-in approach to participant recruitment, increasingly required by ethics committees, resulted in lower response rates and a biased sample. We propose that the opt-out approach should be the default recruitment strategy for studies with low risk to participants. Low response rates are acknowledged as a potential source of bias in survey results. Response rates are a particular problem in surveys of GPs. Thus, the methods used to encourage response to mailed surveys and the influence of inducements in maximizing response rates are fundamental issues to be examined when addressing the problem of response bias.
                To increase the overall response rate to a national study of GPs and to explore the effects of financial and non-financial inducements on response rates.
                Two mailing waves of a postal questionnaire to a 20% random sample of all GPs in England and Wales had achieved a 33% response rate. For the third mailing wave, the non-responding GPs were then divided into a control group, a group who were offered a donation to charity to complete the questionnaire and a group who were offered cash. The charity and cash groups were further subdivided into 5 pounds and 10 pounds groups to assess the effect of the size of the inducement offered. For the control group, a fourth wave was sent the offer of a 5 pounds or 10 pounds incentive.
                Response was positively affected by the offer of an inducement. Cash, however, had a more substantial effect than the offer of a donation to charity. Older GPs were less likely to participate overall, whereas male GPs were more likely to respond to a cash inducement. Doctors who had seen more patients were less likely to reply earlier and were more likely to respond to the offer of cash.
                Primary care is going through many changes, some of which have increased the workload of the GP. It may now be that, to achieve the response rates needed to validate policy-related research, the offer of inducements will become a necessary part of the research process. To describe factors that influence participation by general practitioners (GPs) in survey research, and in particular to examine the effectiveness of telephone prompts made by a GP researcher compared with non-medical researchers in a survey of GPs on sexually transmissible diseases (STDs).
                A questionnaire survey of knowledge, attitudes, behaviour and practice (KABP) in relation to STDs was distributed to 520 Victorian GPs randomly selected from the Australian Medical Publishing Company's (AMPCo) database of Australian medical practitioners.
                Number of GPs able to be contacted by telephone and cumulative and overall response rates to the questionnaire.
                The overall response rate was 85%. Although the GP researcher was able to make contact by telephone in a higher proportion of cases (80%) than the non-GP researchers combined (69%, p < 0.01) response rates were not significantly different (83% versus 87%).
                Telephone prompts to encourage GP response in survey research need not be made by a medical practitioner. Other important factors in relation to response rate that should be considered by researchers are GP involvement in the developing and piloting of the survey instrument, incentives and provision of detailed feedback of the results of the survey. This study assessed differences in response rates to a three-wave mail survey when signed or unsigned postcards were the third wave of the mailing (after two mailings of the questionnaire). A total of 259 signed postcards and 259 unsigned postcards were mailed as the third-wave mailing. There were 34 signed postcards and 30 unsigned postcards returned, a not significantly different distribution by chi-square test. To examine the association between questionnaire length and response rate in a mailed survey of generalist physicians randomly selected from the American Medical Association master file.
                In a pilot study, otherwise similar questionnaires of 30 different lengths (849 to 1,867 words) were mailed to 192 physicians in April 1999. In the main study, questionnaires of 16 different lengths (564 to 988 words) were mailed to 1,700 physicians between June 1999 and January 2000.
                In the pilot study, response rate decreased from 60% for questionnaires 849 words in length to 16.7% for questionnaires over 1,800 words in length. Logistic regression revealed an odds ratio of 0.887 (95%CI 0.813, 0.968; p=0.006) for word count, expressed in units of 100 words. In the main study, response rate varied between 51.5% and 71.4%. Logistic regression showed no association between response and word count (OR 0.988; 95%CI 0.896, 1.090; p=0.81).
                There appears to have been a threshold in these studies of approximately 1,000 words. Questionnaires above the threshold had lower response rates than those below it (38.0% vs. 59.4%). Mail surveys of physicians have been characterized by lower response rates than general population surveys, raising concerns about nonresponse bias. Although monetary incentives have routinely been used to improve survey response among physicians, questions remain regarding how much of an incentive is most cost-effective. The present study seeks to further examine the effects of incentive size on response rates to a national mail survey of physicians.
                This study used a random sample of 873 physicians practicing in the United States; the response rate was 65% (n = 563). Respondents were randomly assigned to receive a $5, $10, or $20 cash incentive in the initial mailing. Except for the magnitude of the incentive, the procedures for each condition were identical, with each respondent receiving up to 3 follow-up mailings and 2 telephone calls.
                Overall response rates ranged from 60.3% for the $5 incentive category to 68.0% for the $10 incentive category. Differences in overall response rates across the incentive categories, however, were not significant. Higher levels of incentives also did not significantly reduce the number of mail and/or telephone interventions required to reach the target response rate of 60.0%. As expected, aggregate costs (excluding labor) were lowest for the $5 incentive group.
                Our findings suggest that changes in the magnitude of incentive do not automatically result in increases in survey response among physicians. Possible reasons for this lack of effect as well as alternatives to monetary incentives are addressed. The purpose of this study was to investigate how response rates to a postal questionnaire are affected by title and length of the survey instrument. Five questionnaires, which differed according to title and length, were designed. Each questionnaire was mailed to a random sample of one thousand Norwegian women aged, 35-49 years. A total of 3,106 questionnaires were returned (62.1%). The highest response rate (70.2%) was achieved by a two-page questionnaire entitled "Women and Cancer". An otherwise identical questionnaire entitled "Oral Contraceptives and Cancer" had a response rate of 60.7%. Questionnaires entitled "Women and Cancer" with a length of four and six pages had a response rate of 62.8% and 63.3%, respectively. The four page questionnaire entitled "Women, Lifestyle and Health" had the lowest response rate of 57.1%. This study shows that in a general population of Norwegian women the title of a postal questionnaire influences the response rate. The results indicate that although the shortest questionnaire had the highest response rate, the most extensive survey instrument did not have the lowest response rate. The distribution of risk factors for breast cancer did not vary according to response rate or design of questionnaire. The overall findings of this study suggest that the benefits from the increased information obtained from extensive postal questionnaires out-weighs a potential non-response bias due to a somewhat lower response rate. nan nan Mailing surveys to low-income populations is often avoided because of concern about low response rates. In this study, the authors used a mailed survey of a low-income population to test whether $1.00 or $2.00 cash-response incentives were worth the expense and whether 2-day priority mail ($2.90 postage) would yield a sufficiently higher response rate than certified mail ($1.52 postage) to justify its cost. In 1994, 2,243 randomly selected families in subsidized health care programs in Pierce County, Washington, were randomly sent no incentive, $1.00, or $2.00 in the first of three mailings. For the third mailing, nonrespondents were randomly assigned to receive either certified or 2-day priority mail. After 4 weeks, the response rates were 36.7%, 48.1%, and 50.3% for the no-incentive, $1.00, and $2.00 groups, respectively. After three mailings, the cost per response was the lowest for the group that received $1.00. The response rate for the certified mailing (28.1%) was significantly higher than the rate for the more expensive priority mailing (21.7%). No incentive-related bias was detected. The authors concluded that the most efficient protocol for this low-income population was to use a $1.00 incentive in the first mailing and a certified third mailing. Return rates were studied for a survey on the perceived professional preparation of therapeutic recreation specialists by directors of college and university recreational therapy programs. Specifically, returns for surveys with self-addressed, stamped return envelopes enclosed were compared to those with self-adhering return address labels. Of the 75 surveys sent with a self-addressed, stamped return envelope, 42 responses (56%) were returned at a cost of $2.58 per respondent. Of the 72 surveys sent with a self-adhering return address label 43 responses (59.7%) were returned at a cost of $1.56 per response. While there was no significant difference in return rates, the self-adhering return address label was more cost effective than the self-addressed, stamped, return envelopes. To evaluate response-aiding strategies feasible in large surveys, we randomly allocated general practitioners (GPs) to one of four intervention groups: Group 1 received 'exhaustive' telephone prompts by a medical peer in advance of a questionnaire; Group 2, inclusion of an embossed pen with the questionnaire; Group 3, an advance letter prompt; and Group 4, a 'single attempt' advance telephone prompt by a non-medical research assistant. Follow-up procedures were identical. Response rates by group were not significantly different overall (chi 2 = 4.59, df = 3, p = 0.20) although advance prompts by a medical peer were significantly more effective than other strategies for male GPs. The difference in overall response rates between males (63%) and females (74%) was significant (chi 2 = 15.40, df = 1, p < 0.01). No other response bias was evident. Our demonstration of a significant interaction between respondent sex and response-aiding strategy invites further research. nan Collecting saliva samples by mail can serve numerous purposes in epidemiologic research. The objectives of this study were to assess what proportion of participants in a mail survey would provide a saliva sample and whether incentives could improve participation. In 1995, 2,994 students, faculty, and staff members of Geneva University, Geneva, Switzerland, were randomized to receive, together with a mailed questionnaire about smoking, a saliva vial, a ballpoint pen, the offer of a lottery, or any combination of these. After one mailing and a reminder letter, response rates were 52% among those who had been requested to provide saliva and 63% among controls (p < 0.001). In the former group, most respondents (98%) provided a saliva sample. Incentives improved participation only among those who were asked to provide saliva (lottery: +11% response, p = 0.003; pen: +6% response, p = 0.1). The final participation, after up to three reminders, was 76% overall. The authors conclude that while the collection of saliva samples by mail is feasible it tends to decrease response rates. We conducted a randomised trial to determine the differential effectiveness of a telephone prompt by a medical researcher compared with a nonmedical research assistant in improving response rates of general practitioners to a survey and to compare personnel costs. A national random sample of Australian general practitioners was allocated randomly to two intervention groups. In advance of a self-administered questionnaire, Group A (n = 184) received a telephone prompt by a medical researcher and Group B (n = 189) a prompt by an experienced nonmedical research assistant. Other aspects of survey administration were identical for both groups. The five-month cumulative response rate obtained by the medical researcher (81 per cent) was not significantly different from that of 72 percent obtained by the research assistant (chi 2 = 3.3, 1 df, P = 0.07). For Group A, 279 telephone calls, consuming 23 hours 15 minutes, were made. Group B required more calls (384) and more time (32 hours). Using the relevant award pay scales, the estimated personnel costs for each group were $631 and $601 respectively. We conclude that an experienced nonmedical research assistant is as effective as a medical practitioner in administering telephone prompts to enhance survey response rates, although savings are not necessarily made. Generic and condition-specific measures of quality of life are often used in parallel. Despite extensive evidence of question ordering effects in the general survey literature, there is no consensus on which type of measure should be administered first and little previous conclusive research into instrument ordering effects.
                To investigate the effects of instrument ordering on response rates, speed of response, and response patterns to questions on health-related quality of life.
                Subjects were randomized to two different versions of a self-completion questionnaire; in the first, condition-specific measures of quality of life preceded generic instruments; in the second version, the relative positions were reversed.
                Adults with asthma or angina from 62 family practices in northeast England.
                Instruments were the generic Medical Outcomes Study Short Form 36-item questionnaire, the EQ-5D, the Newcastle Asthma Symptoms Questionnaire, the Asthma Quality of Life Questionnaire, and the Seattle Angina Questionnaire. Effects were assessed in terms of questionnaire response rates, speed of response, item nonresponse rates, internal consistency, and domain scores on the quality of life measures.
                Instrument ordering had no effect on questionnaire response rates or response speed. Only condition affected item nonresponse rates. Some ordering effects in respect of quality of life scores were observed, but these were inconsistent within and between conditions, and none of the differences were clinically significant.
                There is little effect of instrument ordering on responses to self-completed measures of quality of life. Further research is required to test whether this finding extends to other methods of administration. It is cheap to process epidemiological data from optical mark read (OMR) questionnaires. Respondents should use a pencil to complete OMR questionnaires, but many will not unless these are supplied. Sending pencils and erasers is expensive. Does sending pencils and erasers increase the response rate as cost-effectively as sending reminders, or does this decrease the error rate and offset data checking costs? We mailed 300 smokers and half were randomised to receive pencils and erasers. The relative risk (95% confidence intervals) for the response rate for the pencil group relative to the non-pencil group was 0.77 (0.46-1.29) and for the error rate was 1.31 (0.78-2.21). Sending pencils and erasers was not cost-effective in sensitivity analysis with any response rate or using the confidence intervals. Including pencils with mailed epidemiological questionnaires probably has no benefit and any plausible benefit does not offset the costs of sending pencils and erasers. Mailed questionnaires are an economical method of data collection for epidemiologic studies, but response tends to be lower than for telephone or personal interviews. As part of a follow-up study of volunteers who provided a brief health history and blood sample for a blood specimen bank in 1989, the authors conducted a controlled trial of the effect of length, incentives, and follow-up techniques on response to a mailed questionnaire. Interventions tested included variations on length of the questionnaire, effect of a monetary incentive, and effect of a postcard reminder versus a letter accompanied by a second questionnaire. Response was similar for the short (16-item, 4-page) and long (76-item, 16-page) questionnaire groups. The non-monetary [corrected] incentive did not improve the frequency of response. The second mailing of a questionnaire was significantly better than a postcard reminder in improving responses (23% vs. 10%). It is important to systematically test marketing principles to determine which techniques are effective in increasing response to mailed questionnaires for epidemiologic studies. nan This paper describes how a sample of elderly people were identified from the electoral register using an initial postal screen, and reports a technique that was used to increase the response to the screen. The effects of a number of controllable factors on the response rate of mothers to a postal questionnaire were assessed by a series of experiments. In one a factorial design was used to look at seven factors with a random sample of 1600 mothers. The main findings were that the responses to questionnaires of 8, 16 or 24 pages were similar, but that rather more mothers replied when the questionnaires contained only factual questions than when they covered both facts and attitudes. Another experiment, based on a similar sample, compared the response rates when the questionnaires were sent out by a government organization or by the Institute for Social Studies in Medical Care, and found no difference. The final experiment looked at the effect of precoding the answers or asking respondents to tick boxes beside their replies and again found no difference in response rates. The overall response rate was 79 per cent, but this varied between 66 and 87 per cent in the ten randomly selected study areas--a much greater variation than that found with any of the experimental factors. Evaluate an advance notice letter for enhancing patient satisfaction survey response rates in African Americans and Whites.
                Randomized trial of an advance notice letter (versus no letter) mailed two weeks prior to a mail satisfaction survey in a random sample of 600 African American and White patients ages 50 and older, stratified by ethnicity, sex, and age.
                The advance letter was independently associated with a completed survey in Whites (odds ratio = 2.73; 95% confidence interval [CI] 1.66, 4.50), but not in African Americans (odds ratio = 1.24; 95% CI 0.76, 2.02). Being male was independently associated with returning a survey in Whites (odds ratio = 1.86; 95% CI 1.13, 3.06). Younger age (odds ratio = 0.98; 95% CI 0.96, 0.99) was independently associated with a completed survey in African Americans.
                An advance letter prior to a satisfaction survey is associated with increased response rates in Whites, but not in African Americans. Low response rates, especially among physicians, are a common problem in mailed survey research. We conducted a randomized trial to examine the effects of cash and lottery incentives on response rates. A total of 4,850 subjects were randomized to one of three interventions accompanying a mailed survey-no incentive (n = 1,700), cash payment [three levels of Hong Kong dollars (HKD) $10, $20, and $40; N = 50 in each subgroup], or entry into a lottery (three levels of HKD$1,000, $2,000, and $4,000; N = 1,000 in each subgroup) on receipt of the completed questionnaire. The response rates were higher among those offered incentives than those without (19.8% vs. 16.8%, P =.012). Cash was the more effective incentive compared to lottery (27.3% vs. 19.4%, P =.017). Response also increased substantially between the first and second mailings (14.2% vs. 18.8%, P >.001). In addition, those with specialist qualifications were more willing to participate in mailed surveys. We found no significant differences in response outcomes among the various incentive arms. Cash reward at the $20 level was the most cost-effective intervention, in terms of cost per responder. Further systematic examination of the effects of different incentive strategies in epidemiologic studies should be encouraged. Low response rates to postal questionnaires can threaten the validity of studies by reducing the effective sample size and introducing bias. The identification of methods with which to optimise response rates could, therefore, improve the quality of studies. In an attempt to identify such methods, we undertook a randomised trial of two simple variations in questionnaire design.
                Using a 2 x 2 factorial design, we conducted a randomised trial to test two variations in questionnaire design; the questionnaires were printed on either single-sided or double-sided paper and had either a single- or multiple-booklet layout. Using equal random allocation, 3836 women were randomised to receive one of these questionnaires as part of a study investigating risk factors for osteoporotic fractures.
                One thousand eight hundred and seventy questionnaires were returned, giving an overall response rate of 48.7%. There were no significant differences in the overall response to each of the four questionnaire designs. When the number of responders who completed at least 50% of each of the three sections was identified, it was found that single-booklet questionnaires had a better response than the multiple-booklet questionnaires and that single-sided questionnaires had a better response than double-sided questionnaires. However, these results were not significant at the 5% level. There were no significant differences in the response to questions on the odd (left-hand side) pages for the single- compared with the double-sided questionnaires.
                As the most cost-effective use of resources, we would advocate the use of double- rather than single-sided questionnaires, and use of a single- rather than multiple-booklet design. This two-part methodologic research was designed to evaluate the effects of a financial incentive on questionnaire response rate and response bias for general dentists surveyed by mail. Subjects were 517 clinicians randomly selected from a two-state population of practitioners insured by a single malpractice liability carrier. Subjects received a check for either $5 or $10 in the original mailing. In Study 1, a single mailing and postcard follow-up resulted in a 57.8 percent (111/192) response rate. In Study 2, employing Dillman's Total Design Method, a 69.6 percent (208/299) response was obtained after a third mailing. Analysis of response rate by incentive level in each study revealed no significant differences. In contrast, early responders (first mailing and follow-up postcard) differed from late responders (second and third mailings) on age (41.4 vs 37.0 years; T = 2.17; P = .032), non-Caucasians (27.7% vs 63.9%; chi 2 = 17.3; df = 4; P < .002), females (13.9% vs 27.8%; chi 2 = 3.9; df = 1; P < .05), foreign-trained (7.0% vs 19.4%; chi 2 = 16.5; df = 2; P < .001), and dissatisfaction with practice (31% vs 51%; chi 2 = 7.8; df = 4; P = .10). Thus, the magnitude of the financial incentive in this experiment had no differential effect on response rate. But differences in responses from late responders (proxies for nonresponders) on demographic characteristics and key study variables suggest the persistence of response bias despite an acceptable response rate. Future dental health survey research should employ tests for response bias on both sets of variables. The study objective is to evaluate the effect of monetary incentives on response rates of adolescents to a smoking-related survey as the first step toward participation in an intervention trial.
                A sample of 4,200 adolescent members of a managed care organization were randomized to one of four incentive groups: a $2 cash group, a $15 cash group, a $200 prize drawing group, or a no-incentive group. We compared group-specific response rates and willingness to be contacted about future study activities, as well as costs.
                Incentives increased survey response rates (55% response without incentive vs. a 69% response with incentive), with response of 74% in the $15 cash group, 69% in the token group, and 63% with a prize incentive. Incentives did not adversely affect willingness of adolescents to be contacted about a smoking intervention, (65% willing with incentives vs. 60% without, P = 0.03). In terms of cost per additional survey completed, token and prize groups were marginally more expensive than the no-incentive group ($0.40 and $1.42, respectively) while the large cash incentive was substantially more costly ($11.37).
                Monetary incentives improve response rates to a mailed survey, without adverse impact on willingness to further participate in intervention activities. However, a variety of issues must be considered when using incentives for recruitment to intervention studies.
                Copyright 2000 American Health Foundation and Academic Press. nan It is important to maximize response rates to postal questionnaires. We compared the impact of three low-cost interventions on response rates.
                A 2 x 2 x 2 factorial trial was conducted, nested within TOMBOLA (Trial Of Management of Borderline and Other Low-grade Abnormal smears). Three interventions were evaluated: (1) enclosing a TOMBOLA-branded pen with the questionnaire (as opposed to no pen); (2) sending the questionnaires by first class post (as opposed to second class); and (3) enclosing a preaddressed return envelope on which there was a second class postage stamp (rather than a freepost business-reply envelope). Nine hundred thirty women, aged 20-59 years, due to receive a TOMBOLA psychosocial questionnaire by post during June-August 2003 were randomized.
                Enclosing a pen resulted in a statistically significant 7.0% increase in the cumulative proportion of questionnaires returned (from 61.5 to 68.5%; P = .002). The adjusted odds of response was significantly raised (odds ratio [OR] = 1.38, 95% confidence interval [CI] 1.04-1.82). Neither first class post nor providing a stamped envelope had a significant impact on response. There were no interactions between the interventions.
                Enclosing a pen with a questionnaire can significantly increase response. This low-cost strategy was effective against a background of "good practice" with regard to the administration of postal questionnaires. To compare tracing and contact rates using alternative incentives in a computer-assisted telephone interview (CATI) survey among postpartum women.
                In a randomized trial of 1,061 postpartum women 18-49 years of age selected from four Iowa counties, we compared the effects of: (1) unconditional $5 telephone card incentive enclosed with the introductory letter followed by $25 incentive conditional upon successful telephone tracing, contact, and completion of CATI (Group 1, n = 530) vs. (2) $30 incentive conditional upon subject completion of CATI (Group 2, n = 531).
                Overall telephone tracing and contact rates achieved were 67.8% and 66.6%, respectively. Tracing (70.2 vs. 65.4%, P = .09) and contact (68.5 vs. 64.8%, P = .26) rates were consistently higher among subjects assigned the combination of a conditional and an unconditional incentive. The combined incentive type had a greater impact on telephone tracing success rates for subjects on whom we could not initially locate an active telephone number (16.7 vs. 7.3%, P = .07) when compared to subjects for whom we found an active telephone number at the time of mailing the introductory letter (78.9 vs. 75.9%, P = .30).
                Combining conditional and unconditional recruitment incentives can facilitate telephone tracing efforts in surveys conducted among recently postpartum women. To evaluate the use of a self-administered quantitative food frequency questionnaire (QFFQ) in a national dietary survey concerning (a) response rates with different distribution methods and reward; (b) degree of underreporting of energy intake; (c) reproducibility of the QFFQ; and (d) seasonal variation on reported intake.
                A pilot study was performed in 1992 to test response rates to the QFFQ with three different distribution methods, with and without reward, in a random sample of 1200 adults aged 16-79 y. In another study, the QFFQ was distributed to a nation-wide, representative random sample of 5008 adults aged 16-79 y during June, September, November 1993 and March 1994. Reproducibility was evaluated among 90 responders to the survey who answered another QFFQ six weeks later.
                The distribution method combining postal distribution and collecting the QFFQ by interviewer as well as an offer to participate in a lottery, gave the highest response rate (72%). The possibility to get a reward increased the response rate by 9, 14 and 57%, respectively, depending on the distribution method used. The mean daily energy intake and the percentage of subjects claiming to have unlikely low energy intake did not differ significantly between the different ways of distribution. In the main survey the mean ratio between energy intake and estimated basal metabolic rate was 1.58 among men and 1.47 among women, and 37% of men and 45% of women had a ratio below 1.35. Spearman rank correlations between the two QFFQ ranged from 0.48 (edible fats) to 0.91 (coffee) with a median coefficient of 0.70. For nutrients correlations ranged from 0.55 (carbohydrate E%) to 0.81 (alcohol), with a median coefficient of 0.72. The season of questionnaire administration was of minor importance for the reported intake of the main foods and nutrients.
                The QFFQ-method is suitable for use in a Norwegian nutritional surveillance system.
                National Nutrition Council, Ministry for Agriculture, Ministry for Health and Social Affairs and Norwegian Research Council. The purpose of this research was to study the effect of various direct mail techniques on professional nurses' response rates to questionnaires. A random sample of 700 registered professional nurses consisting of five groups who were members of New York State Nurses Association (NYSNA) were mailed a questionnaire with 22 items. The study demonstrated that the response rates were directly attributable to techniques used. Providing information about the association was related to significantly decreased response rates and monetary incentives with significantly increased response rates. A combined direct mailing for questionnaire completion and membership solicitation was not effective for either purpose. The study aimed to consider the impact of two different types of reminder on response rates and costs in a postal survey.
                The study was a cross sectional survey. A self-completion lifestyle questionnaire was used. Those who did not respond after the initial mailing were randomly allocated to receive either a postcard or questionnaire as a first reminder. All outstanding non-responders received a questionnaire as a second reminder.
                A representative sample of 698 adults aged 16-70 was used, drawn from a family health services authority register.
                Postcard reminders were as effective as questionnaire reminders in increasing response whether one or two reminders are sent. The costs per response were calculated. Two questionnaires as reminders were found to be 1.7 times more expensive than a postcard plus questionnaire. Including the initial mailing, the cost per response using all questionnaires was 1.3 times the cost when a postcard was used for the first reminder.
                To increase the response to a postal survey effectively and economically, two reminders should be sent--first a postcard and then a questionnaire. Although colorectal cancer screening by using a fecal occult blood test (FOBT), flexible sigmoidoscopy, colonoscopy, or barium enema x-ray reduces the incidence of and death from colorectal cancer, the rate of colorectal cancer screening in the general population is low. We conducted a randomized trial consisting of direct mailing of FOBT kits to increase colorectal cancer screening among residents of Wright County, Minnesota, a community in which colorectal cancer screening was promoted.
                At baseline, we mailed a questionnaire about colorectal cancer screening to a random sample of Wright County residents aged 50 years or older who were randomly selected from the Minnesota State Driver's License and Identification Card database (estimated N = 1451). The sample was randomly allocated into three equal subgroups: one group (control) received only the questionnaire, one group received FOBT kits by direct mail with reminders, and one group received FOBT kits by direct mail without reminders. Study participants were sent a follow-up questionnaire 1 year after baseline. We used the responses to the questionnaires to estimate the 1-year change in self-reported screening rates in each group and the differences in the changes among the groups, along with the associated bootstrap 95% confidence intervals (CIs).
                At baseline, the estimated response rate was 86.5%, self-reported adherence to FOBT guidelines was 21.5%, and overall adherence to any colorectal cancer screening test guidelines was 55.8%. The 1-year rate changes in absolute percentage for self-reported adherence to FOBT use were 1.5% (95% CI = -2.9% to 5.9%) for the control group, 16.9% (95% CI = 11.5% to 22.3%) for the direct-mail-FOBT-with-no-reminders group, and 23.2% (95% CI = 17.2% to 29.3%) for the direct-mail-FOBT-with-reminders group. The 1-year rate changes for self-reported adherence to any colorectal cancer screening test were 7.8% (95% CI = 3.2% to 12.0%) for the control group, 13.2% (95% CI = 8.4% to 18.2%) for the direct-mail-FOBT-with-no-reminders group, and 14.1% (95% CI = 9.1% to 19.1%) for the direct-mail-FOBT-with-reminders group.
                Direct mailing of FOBT kits combined with follow-up reminders promotes more rapid increases in the use of FOBT and nearly doubles the increase in overall rate of adherence to colorectal cancer screening guidelines in a general population compared with a community-wide screening promotion and awareness campaign. This study examined cancer survey return rates in relation to race-specific versus general stamps used on self-addressed stamped return envelopes. Of the 104 race-specific stamps sent 41 (39%) were returned. Of the 108 general stamps sent 41 (38%) were returned. Thus, race-specific stamps were not effective in increasing return rates in this sample of African-American women. nan To investigate the effect of font size and paper thickness on the response to, and completion of, a self-completion postal questionnaire among older people with joint pain.
                Randomized trial. People aged 50 years and older with joint pain who consulted a general practitioner at one of five general practices in Central Cheshire were sent a postal questionnaire. Questionnaire format (large or small font size, thick or thin paper) was randomly allocated using a 2 x 2 factorial design.
                Questionnaires were received from 502 out of 650 participants (crude response 77%). Response was significantly higher for participants receiving questionnaires with a larger font size (79.3% vs. 75.2%; hazard ratio 1.26, 95% confidence interval: 1.02, 1.56). Paper thickness had no significant effect on response. Completion (measure by assessing double-page turnover error) was increased in participants receiving questionnaires printed on thicker paper (3.2% vs. 7.1%; P=0.049) but was not affected by font size.
                This study demonstrates that questionnaires in larger font and on thicker paper may produce higher and more complete responses than surveys using standard size font and standard thickness paper, and should therefore be considered in studies among older people. A major disadvantage of the mail survey in medical research is non-response, which may introduce bias. This study measured the effect of two simple factors on the response rate to a questionnaire concerning headache and migraine in a survey of 2,508 electors. The two factors were the class of postage and the colour of envelopes used; neither was found to have a significant effect. It was concluded that cheaper mailing methods are not likely to jeopardise response. nan nan nan Mailed surveys are widely used to collect epidemiologic and health service data. Given that nonresponse can threaten the validity of surveys, modest incentives are often used to increase response rates. A study was undertaken among childhood cancer survivors and their parents to determine if response rate to a mailed survey differed with provision of immediate versus delayed incentives.
                A self-administered survey designed to ascertain health behaviors was mailed to 397 childhood cancer survivors (and their parents if the survivor was <18 years of age). Subjects were randomized into two groups based on gender, age, race, and cancer type. One group received a 10 US dollars incentive with their blank survey (unconditional incentive), whereas the other group received the incentive upon receipt of their completed survey (conditional incentive). If children were minors, both the parent and the child received incentives.
                No significant differences in response rates were observed with respect to gender, age, race, or cancer type. However, significant differences in response rates were observed between incentive groups, with unconditional incentives yielding significantly higher response rates than conditional incentives for child survivors who were > or =18 years (64.4% versus 49.0%), as well as younger child survivors (62.5% versus 43.6%) and their parents (64.8% versus 41.5%; all P < 0.05).
                The provision of an immediate incentive generated significantly higher response rates to this mailed health survey among childhood cancer survivors and their parents. Given that survey studies are commonly conducted across various pediatric populations, these findings may help inform the design of future pediatric survey research. This study measures the effect of an intervention to improve mailed survey response rates.
                A randomised controlled trial of a 'primer' postcard was performed as part of a large survey in Victoria in 1997. Prior to the survey mailout, half the sample of 800 general practitioners supplied by the Health Insurance Commission was sent, at random, a primer card to request prompt return of the survey.
                The intervention resulted in a more rapid return of the survey and improved overall response rates from 60% to 66%. The increased cost per returned survey (40 cents) was largely offset by fewer non-responders requiring follow-up.
                A primer postcard is a time and cost-efficient method to increase response rates in general practitioner surveys.
                Public health researchers should consider implementing this intervention to improve response rates to postal surveys. Reports of other response maximising strategies should report the cost per returned survey to allow better comparison. nan nan The authors studied how the introduction of several modifications to a basic food frequency questionnaire can influence the results of dietary surveys. Modifications covered eight combinations based on three levels: increasing versus decreasing order of frequency categories; questionnaires without versus with questions about portion sizes, and questionnaires without versus with extra non-dietary questions. The sample included 6783 women between the ages of 40 and 70 years who took part in mammography screening. The women were randomly assigned to one of the eight study groups. All of the women in each group received one of the eight differently modified questionnaires. The forms extended in length by extra non-dietary questions and portion size categories resulted in a 20% higher total non-response compared to the shorter basic form. Partial non-response was significantly lower for all four questionnaire types that included portion sizes. When portion sizes were included in the questionnaire, the reported mean frequency of consumption was significantly reduced for fat (-10 times per month), milk (-6), bread (-5), vegetables (-2) and fish (-0.4). The decreasing order of responses to the frequency categories was associated with a statistically significant increase in the frequency responses for bread (2.6 times per month), vegetables (2) and fish (0.6). These data provide evidence that the design and extension of food frequency questionnaires influence the results of dietary studies. To assess the effect of the colors of the envelope and ink on the response rate to a postal questionnaire in a study screening for undiagnosed parkinsonism in people aged 65 years and over in the community.
                A total of 2,524 people aged 65 years and over from five general practices in Aberdeen were randomized to receive a questionnaire about the symptoms of parkinsonism printed in either colored (green) or black ink, and sent out in either a brown or white envelope.
                The overall response rate was 63.5%. There was no significant interaction between envelope and ink color. The use of green ink compared to black significantly increased the response rate from 61.4% to 65.7% (OR 1.20, 95% confidence interval 1.02, 1.41). There was no overall effect of envelope color on response rate (62.3% brown and 64.8% white, OR 0.90, 95% confidence interval 0.76, 1.06) but there was significant heterogeneity between the general practices. When this general practice-envelope interaction was accounted for, brown envelopes had a significantly lower response rate than white ones (OR 0.49).
                This study, along with existing evidence, has shown that the use of certain ink colors in postal questionnaires is likely to increase response rates relative to black ink. The effect of envelope color was inconsistent both within this study and between previous studies. This study assessed differences in response rate when the author of a survey was identified as a graduate student or a faculty member. A survey on research ethics was mailed to 500 nurse faculty members with half of the covering letters signed as a graduate student and half signed as a faculty member. There were 388 (78%) out of a possible 495 surveys returned. The response rate was 78% for graduate student and 77% for faculty identifications, not significant by chi-square test. Given the weaker ties to community as noted by scholars such as Robert Putnam, survey researchers should not be surprised by a decline in survey participation over the past 10 years. This research analyzes the use of incentives coupled with introductory themes emphasizing cooperation and helpfulness--cooperative norms in American society--to understand their effects on survey response. This article analyzes two separate experiments (one phone and one mail) that provide evidence that norms of cooperation matter in the decision to participate in a survey, suggesting that this is particularly true at the refusal conversion stage. These results indicate that survey researchers may use such themes to their advantage, especially when conducting a nonresponse follow-up in a mail survey. Previous experimental research in other topic areas has shown that the choice of response alternatives can influence respondents' reporting of the frequency of vaguely defined events and that the set of response alternatives is treated as information in the interpretation of the question. The aim of this study was to examine whether such affects would occur in the context of respondents reporting of health-related events using high and medium frequency closed format response categories, which might be used interchangeably by researchers. The study consisted of a postal survey of n = 518 patients aged > or = 18 years randomly selected from the patient list of a diabetes centre and who were equally and randomly allocated to one of three conditions (Condition A: high frequency response alternatives/horizontal orientation; condition B: medium frequency response alternatives/horizontal orientations; condition C: high frequency response alternatives/vertical orientation). Testing for the effect of response alternatives for the combined responses of five vaguely defined questions between conditions A and B was chi 2 = 5.5, p = 0.019, for the difference in proportions, indicating that overall, those respondents presented with response alternatives discriminating at medium frequency, reported significantly fewer target events than those presented with high frequency response alternatives. Testing for the effect of orientation of the combined question responses between conditions A and C, differences in proportions between conditions, did not reach statistical significance (p > 0.05). Findings from this and previous studies indicate that response alternatives provide information on the interpretation of vaguely defined questionnaire items and that their choice should not be left to intuition alone when designing questionnaire items. To study questionnaire length, type of consent, approach to recruitment, and subject characteristics on participation in epidemiologic studies.
                As part of a health survey among Dutch subjects treated for ear, nose, and throat disorders in childhood, we conducted a pilot study of 200 individuals who were randomly assigned to one of four categories, defined by length of questionnaire (long vs. short) and type of consent form (basic vs. multi-option). In addition, among 8402 subjects eligible to be in the main study (average age 41 years in 1997), we examined the effect of approach to recruitment and subject characteristics on participation rates.
                The pilot study showed a non-significant 10% increase in participation rate using the shorter questionnaire, but no differences by type of consent form. In the full survey, the participation rate was 49% after the first mailing. Response increased by 15% after a written reminder and by 10% after a telephone survey. The total participation rate was 74%. Attained age, sex, exposure status, age at exposure, and response to an earlier survey were determinants of participation rates. Among male non-participants, outright refusal was less frequent than non-response. The refusal rate, unlike the non-response rate, was positively associated with older age at time of survey.
                Health survey participation is influenced by questionnaire length, frequency of contact, and subject characteristics. Nonmonetary incentives lead to small increases in response rates to mailed questionnaires. However, inclusion of a pen or pencil, which may be a facilitating factor as well as a reward, has not been shown to improve response to health surveys in prior trials. In 2001 and 2002, the authors conducted two US trials in which a study-logo pen or pencil was randomly included in a second questionnaire mailed to nonresponders to a first mailing. In the first study, of 10,686 nonresponders to a cohort recruitment mailing, response to the second mailing was 55% with inclusion of a pen versus 40% without one (p < 0.001). In the second study, of 141 nonresponders to a pilot follow-up survey conducted 2 years after entry into a cohort, response was 43% with inclusion of a pencil versus 24% without one (p = 0.02). This 15-19 percentage point increase for mailing 2 translated to a 5-6 percentage point increase after the two mailings combined. In a simulated study of three mailings based on these studies, the overall response rate increased by 4 percentage points at no added cost through inclusion of a pencil in the second mailing. The additional cost of the pencil was compensated for by the reduced number of nonrespondents sent packets at the third mailing. This study supports including a study-logo pen or pencil in a second questionnaire mailing to nonrespondents as a cost-effective method of increasing response rates. nan Postal questionnaires are an economical and simple method of data collection for research purposes but are subject to non-response bias. Several studies have explored the effect of monetary and non-monetary incentives on response. Recent meta-analyses conclude that financial incentives are an effective way of increasing response rates. However, large surveys rarely have the resources to reward individual participants. Three previous papers report on the effectiveness of lottery incentives with contradictory results. This study aimed to determine the effect of including a lottery-style incentive on response rates to a postal health survey.
                Randomised controlled trial. Setting: North and West Birmingham. 8,645 patients aged 18 or over randomly selected from registers of eight general practices (family physician practices). Intervention: Inclusion of a flyer and letter with a health questionnaire informing patients that returned questionnaires would be entered into a lottery-style draw for pound 100 of gift vouchers. Control: Health questionnaire accompanied only by standard letter of explanation. Main outcome measures: Response rate and completion rate to questionnaire.
                5,209 individuals responded with identical rates in both groups (62.1%). Practice, patient age, sex and Townsend score (a postcode based deprivation measure) were identified as predictive of response, with higher response related to older age, being female and living in an area with a lower Townsend score (less deprived).
                This RCT, using a large community based sample, found that the offer of entry into a lottery style draw for pound 100 of High Street vouchers has no effect on response rates to a postal health questionnaire. It is important that response rates to postal surveys are as high as possible to ensure that the results are representative and to maximise statistical power. Previous research has suggested that any personalisation of approach helps to improve the response rate. This experiment tested whether personalising questionnaires by hand signing the covering letter improved the response rate compared with a non-personalised group where the investigator's signature on the covering letter was scanned into the document and printed.
                Randomised controlled trial. Questionnaires about surgical techniques of caesarean section were mailed to 3,799 Members and Fellows of the Royal College of Obstetricians and Gynaecologists resident in the UK. Individuals were randomly allocated to receive a covering letter with either a computer printed signature or a hand written signature. Two reminders were sent to non-respondents. The outcome measures were the proportion of questionnaires returned and their time to return.
                The response rate was 79.1% (1506/1905) in the hand-signed group and 78.4% (1484/1894) in the scanned and printed signature group. There was no detectable difference between the groups in response rate or time taken to respond.
                No advantage was detected to hand signing the covering letter accompanying a postal questionnaire to health professionals. The Consumer Satisfaction Questionnaire (CSQ) was developed by Larsen, Atkisson, Hargreaves, and Nguyen (1979) and has been mentioned as a possible "standard scale" for the evaluation of consumer satisfaction with mental health treatment because of its unidimensionality, reliability, validity and ease of use. A mail survey of ex-clients who had terminated treatment during the preceding year from one of six offices of a regional mental health center in the Rocky Mountain area strongly cross-validated these characteristics as well as other results from the consumer satisfaction literature. In addition, based upon evidence from marketing research, a randomly selected half of the ex-clients surveyed was offered a token inducement of two cents for returning the questionnaire while the other half was not. A significantly greater proportion of ex-clients who received the token inducement returned their questionnaires than did those who had not. This approach appears to be promising and further research with it is indicated. The objective was to test two methods of reducing loss of data in follow-up by abbreviating the questionnaire and offering a token monetary incentive. Primary data were collected between September 14, 1998 and July 23, 1999 from an adult psychiatric population, representing about 50% of all patients, all of whom agreed to participate in a quality-assurance monitoring program. Briefer components of the SF-36 Health Status Survey were expected to yield higher return rates than would the SF-36 plus a form assessing amount of treatment received. Small monetary incentives were expected to result in higher return rates also. Patients were randomly assigned to the groups (n = 73 each). Abbreviation of the questionnaire and use of a monetary incentive each reduced attrition by 10%. A diminishing returns effect for both methods was observed. Further study of a possible interaction between the questionnaire's length and monetary incentive is recommended. To assess the effectiveness of a telephone reminder in increasing responses to postal surveys and to calculate the differential costs per completed questionnaire.
                Randomised controlled trial.
                Australian university and rehabilitation medicine practice.
                The trial was conducted in 1999 among the 143 non-respondents to a questionnaire about work related neck and upper body disorders. The questionnaire was sent to two Australian female samples: 200 office workers (Sample A) and 92 former rehabilitation medicine patients (Sample B). A reminder letter, another copy of the questionnaire and a final letter were sent at two week intervals. Half of the non-respondents within each sample were randomly selected to receive a telephone reminder just after the second mailout of the questionnaire. All direct costs were calculated.
                Responses were significantly higher among those who received the telephone reminder intervention (relative risk 2.54, 95% confidence intervals 1.43 to 4.52). Analysed by intention to phone, 47% of non-respondents in Sample A and 38% in Sample B returned a complete questionnaire after the intervention, compared with 21% and 10%, respectively, in the control groups. For the 112 women (combined samples) who returned completed questionnaires before randomisation, the average cost per respondent was AUD14. There was a higher total cost for the intervention groups (AUD851 versus AUD386 for controls), but the significantly higher number of additional completed responses (31 versus 12) resulted in a 15% lower marginal cost per completed questionnaire in those groups.
                Telephone reminders are cost effective in improving responses to postal surveys. There is a growing evidence base on methods to improve response rates in surveys among patients. This study aimed to determine the additional effect of two intensive follow-up procedures compared to a simple follow-up procedure.
                Randomized controlled trial that compared repeated mailing of the questionnaire and a request to explain nonparticipation with a simple reminder card. The study population comprised 955 elderly adults registered with 26 general practitioners in The Netherlands.
                A total of 530 adults (56%) returned the questionnaire within 3 weeks and a total of 640 (67%) after follow-up. Repeated mailing of the questionnaire had additional effect compared to the simple reminder card in the group of initial nonresponders (relative risk=1.60, 95% confidence interval: 1.11-2.31), but not regarding the overall response rate. A request to explain nonparticipation did not have additional effect.
                Repeated mailing of the questionnaire increased the effectiveness of follow-up among initial nonresponders. Insufficient response rates are a frequent problem in mailed epidemiologic health surveys. As part of a health survey of 1,235 young adults conducted from November 1992 through January 1993 in Geneva, Switzerland, a randomized factorial trial was carried out to assess the contributions of two tactics to increase response rates. The first incentive was the promise of sending 10 Swiss francs (7 US dollars) to respondents; the second was a red postcard, mailed 2 days after the questionnaire, which reminded potential participants to complete the questionnaire. The most effective strategy according to interim analysis was to be selected for follow-up mailings. Two weeks after the first mailing, response rates were 65% for those who had received both incentives, 57% for those who had been offered the money reward only, 54% for recipients of the reminder card, and 48% for those who had received neither incentive (p based on chi 2 (3 df) test < 0.001). The relative hazards of responding were 1.34 (95% confidence interval 1.15-1.55) for the money reward and 1.22 (95% confidence interval 1.05-1.41) for the reminder card. Follow-up mailings to all nonrespondents included both incentives. At the end of data collection, 1,007 persons (82%) had returned the questionnaire. The final response rates were 83, 84, 82, and 78% in the four groups, respectively (p = 0.29). Both the promise of a monetary reward and a reminder postcard considerably improved early response rates. The use of both incentives in follow-up mailings brought final response rates above 80%, except for those who had received no initial incentive. Testing various combinations of incentives in the early stages of a mailed health survey may be a generally useful strategy. High response rates from physicians are key to obtaining valid and generalizable data regarding their sexually transmitted disease (STD) diagnosis, treatment, and control practices. A factorial (3 x 2) study was designed using varying cash incentives ($0, $15, $25) and delivery modes (Federal Express, U.S. mail). Surveys, with three follow-up mailings, were sent to a national probability sample of 311 physicians in OB-GYN, family practice, internal and emergency medicine, and pediatrics specialties. Overall, 156 physicians returned completed surveys (56% overall response rate). Significant effects for incentive level (F = 28.2, df = 2, p < .01) and delivery mode (F = 4.1, df = 1, p < .05) existed. Highest response was among physicians in the $25-FedEx condition (81%). High response rates from busy practicing physicians can be achieved if surveys are relevant to clinical practice, sponsored by a reputable organization (the Centers for Disease Control and Prevention), include a monetary incentive, and are delivered by courier. Maximizing the response rate of self-administered questionnaires is key in survey research. We aimed to evaluate the effects of lottery incentive and length of questionnaire on health survey response rates when used in isolation or combined. A random sample of 440 residents in Western Sydney, Australia was randomly allocated to four equal groups to receive or not receive an instant lottery ticket and a long (seven page) or short (one page) questionnaire. The overall response rate was 71.8%. The final response rates were higher among those receiving the short, rather than the long, questionnaire (75.6% versus 68.2%) (P = 0.08); and among those receiving the lottery incentive compared with those not receiving the incentive (75% versus 68.2%) (P = 0.09). By logistic regression analysis, the success of obtaining a completed questionnaire without any follow-up reminders was significantly associated with the lottery incentive but not the questionnaire length (P = 0.03 and P = 0.54, respectively). The difference between lottery and no lottery groups decreased gradually during the follow-up. A lottery incentive is associated with an increased response after the first mailing. A small up-front cost for a lottery ticket may be worthwhile, since it can save further costs by obviating the need for repeated follow-ups. In 1989, the authors tested the effectiveness of two response-enhancing techniques, a postage stamped or franked return envelope and a prenotification letter, in a survey of pregnancy among 10,047 resident physicians in the United States. The techniques were randomly assigned using a factorial design. No significant interactions were observed between the techniques. After two mailings, those who received a stamped return envelope had a response of 71.2%, compared with 68.2% for those who received a franked return envelope (95% confidence interval 1.3-4.9%). Men who received the stamped envelope had a 5.9% greater response than those who received the franked envelope (p less than 0.001), but the type of postage did not influence response among women (p = 0.84); this interaction was statistically significant (p = 0.006). Physicians who received a prenotification letter had a response of 69.0%, compared with 70.5% for those who did not receive the letter (95% confidence interval -3.3 to 0.2%). The authors conclude that seemingly minor changes in survey design could have saved from 12% to 19% of the total cost of the study. As part of a mailed health survey, we investigated the effect on the response rate of a request to explain refusal to participate. Subjects (N = 1,240) were randomized either to receive or not to receive, with the first mailing, a letter requesting an explanation of their decision not to fill out the questionnaire, if they chose that option. There was a slightly higher cumulative response during most of the study from subjects who had been sent the request, but little difference between the two study groups in the ultimate response rate [80% from the intervention group vs 83% from the control group; response rate difference = -3%; 95% confidence limits (CL) = -7%, 1%]. Of 209 individuals who were sent the request and did not return the questionnaire, only 15 (7%) sent back an explanation. A request to explain a refusal to participate in a mail survey neither jeopardized the response rate nor enhanced it. A mailed questionnaire was sent to 2712 subjects asking about respiratory symptoms, and a raffle for three prizes of 50 pounds, 30 pounds, and 20 pounds was organised. The response rate in the 1762 who were told about the raffle was no higher than for 950 subjects who served as controls. Our aim was to analyze monetary incentives and shortening the questionnaire as means of increasing response rates in a mailed follow-up survey 1 year after inpatient psychotherapeutic treatment. Additionally, effects on partial nonresponse and the assessment of treatment outcome were examined.
                In a 2x2 factorial design, a sample of 3,825 patients was randomized to the two following interventions: (1) receiving a prepaid monetary incentive or none; and (2) getting a short or a long questionnaire. Treatment outcome was measured prospectively by a self-assessment instrument for psychopathology.
                When using incentives, the response rate significantly increased by 7.3% (95% confidence interval [CI] 2.6-11.9%). Receiving a short questionnaire led to an augmentation of the response rate of 3.7% (95% CI 0.9-8.3%), which was not significant. The corresponding odds ratios were significantly increased for monetary incentives (1.36; 95% CI 1.30-1.88), and when abridging the questionnaire (1.15; 95% CI 1.01-1.31). However, partial nonresponse and treatment outcome were independent of the two factors.
                Incentives and a shorter questionnaire led to higher return rates but did not affect partial nonresponse and self-report of treatment outcome in a randomized postal survey. Poor response rates affect the validity of results from postal questionnaires. The effect of three controllable factors upon response rates was examined in a recent study of patients' experiences and views of general practitioner services. The factors studied were the institution from which questionnaires were dispatched, the length of the questionnaire and the inclusion of a potentially sensitive question about ethnic origin. Questionnaires sent out by local Family Practitioner Committees were more likely to be returned than those sent out by a London-based independent research unit, but there were no differences in the nature of replies obtained. Neither the length of the questionnaire nor the inclusion of the potentially sensitive question affected response rates. The results of the study indicate that Family Practitioner Committees wishing to carry out postal surveys of users of general practitioner services can obtain satisfactory response rates. Patient surveys are commonly distributed at the end of a multicenter clinical trial. This Antiarrhythmics Versus Implantable Defibrillators (AVID) substudy prospectively explored the relationship between methods used in distributing a survey and the quantity of responses received. AVID was a multicenter, randomized trial comparing survival in arrhythmia patients treated with antiarrhythmic drugs versus implantable defibrillators. At study termination, a patient satisfaction survey was mailed to the 664 surviving participants. Questions included reasons for study participation, study benefits and problems and quality of care. Survey mailings were stratified by four factors in a 2x2x2x2 factorial design: delivery mode (overnight vs. regular mail), certificate of appreciation, timing of administration ("early" vs. "late") and cover letter signed by a physician versus coordinator. Patients were randomly assigned to received one of 16 combinations of these four factors. Clinical characteristics and response rates were evaluated. Patients were more likely to return surveys delivered by overnight mail (75% vs. 68%, p=0.04), with no certificate of appreciation enclosed (75% vs. 68%, p=0.05) and administered close to the time of study closeout (79% vs. 72%, p=0.085). Compared to the 184 nonrespondents, the 456 (71%) respondents were older, Caucasian, lived with others, were high school graduates and less likely to have Medicare/Medicaid or HMO insurance (p<0.03). Physician recommendation was the most common reason cited for trial participation. Main benefits included increased knowledge of their medical condition and improved health. Reported problems included parking, transportation and excess clinic wait time. This randomized study demonstrated that methods of patient survey distribution affect the survey return rate. Additional studies should explore mechanisms for maximizing return rates.
                Copyright 2002 Elsevier Science Inc. To assess whether print format (single-sided vs. double) and sender recognition (known vs. unknown) affect response and completion rates among physician survey respondents.
                Postal survey of 399 members of the Canadian Association of Emergency Physicians; 2 x 2 factorial design.
                Response rate was 69.4%. Single-sided printing yielded 7.4% (odds ratio OR = 1.41; 95% confidence interval CI = 0.90-2.20; P = 0.13), and a known sender yielded a 6.3% greater response rate (OR = 0.73; 95% CI = 0.47-1.14; P = 0.16). Overall item completion was 98.2%; items missed per respondent ranged from 1 to 14 out of 50. Print format and sender recognition interacted in predicting completion rate (OR = 13.33; 95% CI = 3.10-57.4; P = 0.001); completion was higher for double-sided printing with an unknown sender, and for single-sided printing with a known sender. Completion was also lower when response came after later mailouts (chi2(2) = 10.13; P = 0.006).
                Print format and sender recognition both yielded 6%-7% (nonsignificant) response rate differences. Survey completion rate varied even when overall item completion was high. Completion rate was useful for identifying subgroups likely to provide incomplete data (i.e., late responders), and may provide important information for subsequent surveys. Combining factors that on their own improve survey response may have unexpected consequences. nan This study tested the effect of questionnaire structure on response, speed of return, and content of answers in a postal survey. All 259 patients aged 30-59 years who consulted with back pain at four UK general practices from March to June 2001 were randomly allocated to receive either a traditionally or chronologically structured self-completion questionnaire. The response was higher and the returns quicker (P =.05) for the chronologic questionnaire. There were no statistically significant differences in completion rates or scores on the SF-36, Chronic Pain Grade, Hospital Anxiety and Depression Scale, or Roland-Morris Disability Questionnaire between the two types of questionnaire, and test-retest reliability was high for all scales. Changing questionnaire structure to make questions chronologic does not substantially affect the answers given, but may make a questionnaire more acceptable and easier to complete and speed up returns. nan There is little information on the effect of time on the assessment by the patient of quality of anaesthesia care. This study compared the patient's assessment of anaesthesia care after three different periods of time following discharge from hospital. Materials. Three groups of patients were assigned to receive a standardized, validated psychometric questionnaire either 1, 5, or 9 weeks after discharge from hospital. We measured response rate and the total mean problem score of six dimensions.
                Groups 1, 2, and 3 received 748, 743, and 723 questionnaires, respectively. The response rates including one reminder were 67.3 (95% confidence interval [CI] 63.9-70.6%), 64.5% (CI 61.1-67.9%), and 58.9% (CI 55.5-62.4%), respectively (Group 1 vs Group 3, P<0.001, and Group 2 vs Group 3, P<0.05). The total mean problem scores were not significantly different with 17 (CI 1.4%), 17 (CI 1.4%), and 15% (CI 1.3%), respectively. In two out of six dimensions ('Continuity of personal care by anaesthetist' and 'Nursing care in recovery room') significantly less problems were reported after 9 weeks. The other dimensions of the questionnaire showed no consistent differences between groups.
                The response rate is significantly lower at 9 weeks compared with 1 and 5 weeks after discharge. The total mean problem score remains unchanged but certain fields show fewer problems after 9 weeks compared with 1 and 5 weeks. Questionnaires on patient satisfaction with anaesthesia care should be sent within 5 weeks of discharge. Dentists currently practising within the Central Sydney Area were surveyed (n = 179). A randomized controlled trial was conducted to evaluate the effect of an advance telephone prompt (intervention group) compared with an advance letter prompt only (control group) in maximizing the response rate to a self-administered questionnaire. While the overall response rate was 83 per cent, the final response rate (89 per cent) from dentists in the intervention group was significantly higher than that from dentists in the control group (78 per cent) (chi 2 = 4.14, df = 1, p = 0.04). Advance telephone prompts are effective in maximizing the response rates from dentists and are recommended in future surveys of this professional group. nan The purpose of this study was to compare the performance of the 15-item Picker Patient Experience questionnaire (PPE-15) when embedded in a short form instrument as compared with a longer form measure.
                A postal questionnaire survey of patients recently discharged from two hospital trusts was carried out. Patients were randomized to receive the PPE-15 in either a four-page or a 12-page survey instrument.
                A total of 1445 questionnaires were mailed to patients in either four- or 12-page formats. A total of 949 (65.67 per cent) forms were returned. No difference in response rate was found between the two versions of the questionnaire. Item completion and psychometric properties of the PPE-15 were not found to differ significantly between the two arms of the trial.
                In this survey the length of questionnaire in which the PPE-15 was embedded had no impact in terms of response rate or data quality. Consequently, the results suggest that length of questionnaire, up to the 108 items included in the 12-page survey, is unlikely to adversely affect results on the PPE-15. A 4-factor, 16-cell experimental design was used to investigate the relationship between response rates of community hospitals to a survey conducted by the American Hospital Association (AHA) and 4 characteristics of the survey instrument, each varied dichotomously: the perceived length of the questionnaire, the order of questions, the orientation of the appeal made in the cover letter, and the presence or absence of a promise to share the results of the study with respondents. Response rate variations between the various cells were examined and multiple logistic regression was used to analyze the significance of the association between response rates and each of the four survey instrument variables while controlling for the effect of the others. At the same time, control was also maintained for the effects of five institutional characteristics of hospitals which a previous study had shown to have a significant relationship to response: bed size, location within or outside a standard metropolitan statistical area, AHA membership status, type of ownership, and form of control. The perceived length of the questionnaire and the order of questions were found to have a significant effect on response rates, but the orientation of the cover letter and a promise to share the results of the study with the respondents were found to be insignificant. Mailed surveys are widely used to collect epidemiological and health service data on cancer populations. Nonresponse can threaten the validity of surveys and various strategies, including the enclosure of modest incentives, are often used to increase response rates. A study was undertaken to determine whether response rate to a mailed survey differed with provision of immediate versus delayed incentives. A six-page mailed survey to ascertain dietary supplement use was sent to 1402 men who had been diagnosed with prostate cancer. Subjects were block randomized into two groups based on age (< or =65 years versus >65 years), race (white versus nonwhite), and disease status (locoregional versus distant). One group received a 30-min prepaid phone card concurrently with their blank survey (unconditional incentive), whereas the other group received the incentive only on receipt of their completed survey (conditional incentive). A 60% overall response rate was achieved, and no differences in response rates were noted between conditional and unconditional incentive groups (overall, as well as within defined age, race, and disease-defined strata). Nonwhites, however, were significantly less likely to respond than whites (P < 0.0001). In conclusion, acceptable response rates to a mailed survey can be achieved in a general population of cancer survivors using modest incentives. Given no differences in response rates using conditional versus unconditional incentives, the decision to provide immediate versus delayed incentives is one that should be considered on a study-specific basis, and a decision based primarily on cost. Other means, however, appear necessary to achieve acceptable response rates among minority group cancer survivors. This study's goals were to (a) determine whether sending a survey by certified mail results in a higher response rate from physicians compared to sending by first-class mail and (b) evaluate the cost-effectiveness of this method. The study sample was 409 physicians who were nonrespondents to two previous mailings of a medical specialty society survey. Eligible physicians were designated at random to receive a final mailing either by U.S. Postal Service certified mail including a return-receipt postcard or by first-class mail. There was a higher response rate from the certified mail group compared with the first-class mail group (41.3% versus 24.8%; relative risk = 1.66, 95% Confidence interval 1.25, 2.21). A cost-effectiveness analysis showed that the cost per respondent was higher using certified mail versus first-class mail in the third mailing ($2.77 versus $2.34). Thus, use of certified mail is effective in increasing survey response but more costly. To determine whether response rates to a mailed questionnaire sent to population control subjects could be increased through offer of a small incentive, half of the control subjects (n = 477) in a case-control study of renal cell carcinoma were randomly selected to receive a contact letter offering a lottery ticket if a completed questionnaire was returned; the remaining subjects (n = 477) received the same letter but with no mention of a lottery ticket. Overall response rates did not differ between the two groups (72.6% versus 74.4%), although a higher percentage of those offered a lottery ticket responded without follow-up (24.4% versus 18.5%). Binomial regression modeling of the effect of the lottery ticket offer, sex, age, and percent of urban dwellers on response indicated a significant effect only for percent of urban dwellers, the rate of response increasing with a decreasing percentage of urban dwellers. The effect of sex was of borderline significance (P = 0.05), with females having the higher rate of response. Measures of association in prospective studies can be distorted by incomplete follow-up. Various mailing strategies were used to contact 12,233 cohort members of the Health Professionals Follow-up Study who had not responded to three successive bulk-rate mailings. Response rates were highest, 79.5% overall, from participants who were sent a certified mailing in phase 1 (63.2%), followed by a repeat certified mailing to nonrespondents (44.3%). Although altering the physical appearance of the envelope and using other postal rates were tested, certified mail was the most effective approach for reaching study members who were nonrespondents to a mailed questionnaire. The authors conducted a randomized trial in Geneva, Switzerland, to assess whether response rates to a mailed survey could be increased by printing the questionnaire on green paper. The authors also conducted a meta-analysis of 10 experimental studies that tested the effect of colored questionnaires on response rates. The randomized trial showed no effect (relative risk of responding [RR] = 1.00). The meta-analysis showed that mailing questionnaires on pink paper increased response rates by 12% (RR = 1.12, 95% confidence interval = 1.01 to 1.25, p = 0.04). Other colors had no statistically significant effect (blue: RR = 1.03, p = 0.49; green: RR = 1.02, p = 0.23; yellow: RR = 0.96, p = 0.30). Overall, using colored instead of white paper had no effect (RR = 1.02, p = 0.17). Thus, printing questionnaires on colored paper does not substantially increase response rates in surveys, except for pink paper. To assess the effect of incentive size on response rates, data quality, and cost in a digestive health status mail survey of a community sample of health plan enrollees.
                The study population was selected from a database of enrollees in various health plans obligated to receive care at Park Nicollet Clinic-HealthSystem Minnesota, a large, multispecialty group in Minneapolis, Minnesota, and the nearby suburbs.
                A total of 1,800 HealthSystem Minnesota enrollees were randomly assigned to receive a survey with an incentive of $5 or $2. The response rates for each incentive level were determined. Data quality, as indicated by item nonresponse and scale scores, was measured. Total cost and cost per completed survey were calculated.
                The response rate among enrollees receiving $5 (74.3 percent) was significantly higher than among those receiving $2 (67.4 percent); differences were more pronounced in the first wave of data collection. Data quality did not differ between the two incentive groups. The total cost per completed survey was higher in the $5 condition than in the $2 condition.
                A $5 incentive resulted in a higher response rate among a community patient sample with one mailing than did a $2 incentive. However, the response rates in the $2 condition approached the level of the $5 incentive, and costs were significantly lower when the full follow-up protocol was completed. Response rates were marginally increased by follow-up phone calls. The incentive level did not influence data quality. The results suggest if a survey budget is limited and a timeline is not critical, a $2 incentive provides an affordable means of increasing participation. In a follow-up study, only 64% of 126,628 US radiologic technologists completed a questionnaire during 1994-1997 after two mailings. The authors conducted a randomized trial of financial incentives and delivery methods to identify the least costly approach for increasing overall participation. They randomly selected nine samples of 300 nonresponders each to receive combinations of no, 1.00 US dollar, 2.00 US dollars, and 5.00 US dollars cash or check incentives delivered by first-class mail or Federal Express. Federal Express delivery did not achieve greater participation than first-class mail (23.2% vs. 23.7%). In analyses pooled across delivery methods, the response was significantly greater for the 2.00 US dollar bill (28.9%, 95% confidence interval (CI): 25.2, 32.7; p < 0.0001), 5.00 US dollars check (27.5%, 95% CI: 22.5, 33.0; p = 0.0001), 1.00 US dollar bill (24.6%, 95% CI: 21.2, 28.3; p = 0.0007), and 2.00 US dollars check (21.8%, 95% CI: 18.5, 25.3; p = 0.02) compared with no incentive (16.6%, 95% CI: 13.7, 19.9). The response increased significantly with increasing incentive amounts from 0.00 to 2.00 US dollars cash (p trend < 0.0001). The 2.00 US dollar bill achieved a 30% greater response than did a 2.00 US dollars check (p = 0.005). For incentives sent by first-class mail, the 5.00 US dollars check yielded 30% greater participation than did the 2.00 US dollars check (p = 0.07). A 1.00 US dollar bill, chosen instead of the 2.00 US dollars bill because of substantially lower overall cost and sent by first-class mail to the remaining 42,717 nonresponders, increased response from 64% to 72%. Randomized trials were performed in Denmark and The Netherlands to determine the effect of mailed reminders on the response rate in surveys among patients in general practice. In both countries, general practitioners handed out questionnaires to 200 adult patients who came to visit them. An intervention group of 100 patients received reminders at 3 weeks after the visit, whereas a control group of the remaining 100 patients did not receive reminders. The response rate was significantly higher in the intervention groups than in the control group in The Netherlands (86% versus 55%, respectively) but not in Denmark (87% versus 81%, respectively). Mailed reminders can improve the response rate in surveys related to a general practice, but they are not effective in all situations. Traditional measures of socioeconomic status may not be reliable for older people and income may be a useful measure for research into inequalities in health. At the same time, researchers increasingly wish to link survey findings to individual data taken from medical records. For this, consent must be sought. To examine whether questions on household income and seeking consent for medical record linkage affected response rates, a postal health survey of patients aged 65 to 74 was undertaken in an inner London practice. The overall response rate was 62.8%. In this study, the inclusion of an income question or seeking consent to access medical records did not reduce response rates to a health survey among older people. A health-related mailed survey was conducted to investigate the effect of follow-up mailings to response rates. In addition, the answer distributions among early and late respondents were compared to check non-response bias. Approximately 3,000 persons aged 40-64 were randomized into two groups; a questionnaire with four pages (twenty-two questions) was assigned to the first group, and a questionnaire with eight pages (thirty-five questions) to the second group. Both questionnaires contained questions of current health status, health-related practice, smoking status, etc. Follow-up mailings were sent twice to non-respondents. Response rates were increased from 38% to 62% by the first follow-up mail, and to 71% by the second follow-up mail. Although the length of the questionnaire did not affect response rates, response rates among the older subjects was higher than the younger subjects. Positive response to current smoking status was 10% lower among early respondents than late respondents, collected after the second follow-up mailing, and response to regular participation in physical/medical checkup was 15% higher among early respondents, whereas there were few differences for answers to other questions. Odds ratios between current health status and several health-related questions may not be biased by late response. However, increased response rates are needed to prevent non-response bias, because there were some differences in responses from follow-up mailings. To determine whether follow-up phone calls improve response rates to a long questionnaire among black and white subjects.
                Forty black and 39 white Seventh-day Adventist churches were randomized to experimental or control status in a 2:1 ratio favoring the intervention, which is a follow-up phone call to certain church members. Subjects selected from each church were those who had signed up for the Adventist Health Study-2 but not returned a questionnaire 3 months after promotion began. Further returns from a church over the next 3 months, and this increment as a proportion of baseline response, were assessed using t-tests and Poisson regression, respectively.
                Comparing black experimental and control churches, the mean difference was 5.5 returned questionnaires per church (p < 0.01). Among white churches the mean difference was 3.0 (ns). The baseline-adjusted increment, however, was greater by a factor of 3.37 (95% confidence interval, 1.92, 5.93) in the black experimental relative to control churches, but among white experimental churches was 13% (ns) lower than controls. This difference in response by ethnic group was statistically significant (p < 0.01).
                Follow-up phone calls improved response rates among black subjects only. A self-report questionnaire is the most widely used method to assess (in)patients' satisfaction with (hospital) care. However, problems like nonresponse, missing values, and skewed score distributions may threaten the representativeness, validity, and reliability of results. We investigated which of alternative item-response formats maximizes desired outcomes.
                Five formats were compared on the basis of sample characteristics, psychometric properties at the scale and item levels, and patients' opinions of the questionnaire.
                Consecutively discharged patients (n=784) were sampled, of which a representative (sex, age, length of hospital stay) subsample of 514 (65%) responded.
                A 54-item satisfaction questionnaire addressing 12 aspects of care was used. Patients responded using either a 10-step evaluation scale ranging from "very poor" to "excellent" (E10), a 5-step evaluation scale ranging from "poor" to "excellent" (E5), or a 5-step satisfaction scale ranging from "dissatisfied" to "very satisfied" (S5). The 5-step scales were administered with response options presented as either boxed scale steps to be marked or words to be circled.
                E5 scales yielded lower means than S5 scales. However, at the item level, the S5 scale showed better construct validity, more variability, and less peaked score distributions. Circling words yielded fewer missing item scores than marking boxes. The E5 scale showed more desirable score distributions than the E10 scale, but construct validity and reliability were lower.
                No large differences among formats were found. However, if individual items are important carriers of information, a (5-step) satisfaction response scale, with response options presented in words next to each item, appears to be the optimal format. Mailed surveys are a popular means of obtaining data on large populations. In July 1999 a mail survey was conducted among 3000 randomly selected members of the American Society of Hematology to assess their approach to diagnosis and treatment of polycythemia vera. Because the researchers and the study population are members of the same professional organization with a vested interest in the results, we anticipated that the advantages of return stamped postage seen in previous studies would be less significant. The response rate for stamped return envelopes was 38% versus 32% for business reply envelopes. This statistically significant difference (P =.0005) of six percentage points is comparable to previous research. Excluding labor, the total cost per returned survey was $2.62 for business reply envelopes versus $1.82 for stamped return envelopes. We conclude that stamped return envelopes are a more effective and cost-efficient means of procuring data from physician specialists. To evaluate whether small monetary incentives improve physicians' responses to surveys. To the best of the authors' knowledge, no one has evaluated emergency physicians' response rate and cost per participant of a small monetary incentive relative to a chance to win a more substantial sum. The authors compared emergency physicians' responses and per-participant costs between a US 2 dollar bill and a 250 US dollars lottery.
                Two groups of 288 emergency physicians were randomly selected and mailed a survey. Within each group of 288, half received a US 2 dollar bill and the other half received an offer that respondents would be entered into a drawing to win 250 US dollars. Nonresponders received a reminder postcard one week later, and persistent nonresponders received a second mailing of the survey three weeks after the initial mailing.
                Of the 576 surveys that were mailed, nine (2%) subjects were ineligible or undeliverable, leaving 567 eligible subjects, of whom 301 (53%) participated in the survey. The US 2 dollar bill had a substantially higher response rate: 170 (56%) of those receiving a US 2 dollar bill participated versus 131 (44%) of those receiving a chance to win 250 US dollars (95% confidence interval = 5% to 22%; p < 0.001). The US 2 dollar bill offer was less expensive per participant than the 250 US dollars offer. The cost of postage and incentives was 997.33 US dollars for 170 participants, or 5.87 US dollars per participant, for the US 2 dollar bill and 979.29 US dollars for 131 participants, or 7.48 US dollars per participant, for the chance to win 250 US dollars.
                Mailing a US 2 dollar bill incentive produces a better response rate with lower cost per participant than offering a chance to win 250 US dollars. Mailed questionnaires are a quick and cheap means of obtaining data, but they have two disadvantages. They often produce low response rates irrespective of the nature of the group sampled, and they may seem inappropriate for clinical samples with visual problems. High response rates are needed for reliable results and valid conclusions. This paper presents a set of techniques enabling high response rates to be obtained. It also reports research showing that such techniques are appropriate even for the partially sighted. Low response rates to surveys are a problem in general practice. There is evidence that offering GPs incentives improves response rates to postal questionnaires. However, there is less evidence about the most effective form of incentive.
                Our trial aimed to maximize response to a postal questionnaire and to test the most effective form of incentive.
                The study involved a randomized controlled trial of a postal survey
                The incentive of a lottery for six bottles of champagne generated a response rate of 79%. Furthermore, one chance of six bottles generated 9% more responses than six chances of one bottle.
                This study has established that, among incentives for postal questionnaires, one big prize improves the yield more than many small prizes despite the lower odds of winning. It has also confirmed that offering a modest incentive to GPs generates good response rates for postal questionnaires. This study examined return rates for a cancer prevention survey by pediatricians in relation to an informational booklet versus a monetary incentive in the first of a three-wave mailing. Of the 300 surveys sent which included an informational booklet incentive, 189 (64%) were returned. Of the 300 surveys sent which included a $1.00 incentive 227 (79%) were returned, indicating the $1.00 incentive was more effective than the informational incentive in increasing return rates in this sample of physicians. Primary care physicians are increasingly being asked to participate in postal surveys. Difficulties in achieving adequate response rates among physicians have been reported. We investigated the effect of two low-cost interventions on response to a primary care physician postal questionnaire.
                A 2x2 factorial trial was developed within the context of a national survey assessing views and practices of physicians regarding prostate-specific antigen testing. We evaluated questionnaire order (version 1: demographics first, version 2: topic-specific questions first) and written precontact. A national database of primary care physicians was compiled. One thousand five hundred ninety-nine physicians were randomly selected, stratified by health board, and randomized.
                47.9% of eligible physicians completed a questionnaire. There was a statistically significant 5.1% higher response rate among physicians receiving version 1 of the questionnaire than those receiving version 2 (50.6% vs. 45.4%, P=0.05); the adjusted odds of response were significantly raised (odds ratio=1.24; 95% confidence interval=1.01-1.54). Precontact resulted in a nonsignificant 3.6% increase in response (49.8% vs. 46.2%; P=0.16). The interventions did not interact.
                Ordering questionnaires with general questions first can significantly increase response rates, whereas precontact can achieve a modest increase. These strategies may enhance response while adding little to the cost of a physician survey. The feasibility of collecting DNA through the mail from a cohort of current and former smokers was assessed. Also examined was whether monetary incentives would increase response rates. A random sample of 300 subjects, stratified by 20 U.S. communities, was selected to participate. The sampling frame included the 6,726 people who were in both the Community Intervention Trial for Smoking Cessation (COMMIT) between 1988 and 1993 and the follow-up study in 2001, and who consented to being contacted again. Subjects were further randomized within communities to incentive arms of 10 US dollars, 2 US dollars, or 0 US dollars. A total of 110 usable samples were returned (37%), and the 10 US dollars incentive arm had the highest response (43%). Logistic regression revealed no significant predictors of sending a DNA sample, although in a larger study, similar-sized odds ratios would be statistically significant for subjects who received the 10 US dollars incentive and for those who were White, female, or college graduates or whose household incomes were more than 60,000 US dollars per year. The spectrophotometer-determined median DNA yield was 44.93 microg (range=4.00-425.86 microg). Assuming that 50 ng of DNA would be needed for polymerase chain reaction amplification to determine any given genotype, 80-8,517 runs would be attainable. Qualitative findings suggest several methodological improvements to boost response rates. Institutional review board requirements, which are standardized on the inpatient, clinical protocol model, stipulated that noninstitutionally based subjects needed a witness to initial and date every page as well as sign the consent form. This pilot study showed that this requirement could pose some challenges in population-based research. To test the effect of a AU dollars 2 scratch lottery ticket on response rates to a national mailed questionnaire of Australian general practitioners (GPs) and medical specialists.
                A randomized controlled trial was conducted and the incentive sent to half of the participants with the first mailing. A single follow-up mailing without incentive was sent to all non-respondents. Survey respondents were then informed of the research question regarding incentives and allowed to withdraw their study data. Differences in response rates between doctors receiving and not receiving the incentive, and between respondents and non-respondents, were examined.
                The overall response rate was 47% (443 respondents). Twenty-two respondents (5%) withdrew their data after being informed of the research question. Of the remaining 421 respondents, 233 had received the incentive (response rate 49.7%) and 188 had not (40.1%, p=0.0032). The absolute increase in response rate with the incentive (9.6%, 95%CI 3.2, 15.9) was quantitatively similar in effect to the reminder mailing (11.8%). The incentive had a larger effect among the GP sample compared with specialists (13.4 vs. 5.9%), although the difference was not statistically significant (p=0.20). There were no systematic differences in demographic characteristics between respondents and non-respondents.
                Increased response rates associated with a small incentive may reduce the need for a second mailed reminder, but strong views about the use of incentives may negatively influence the participation of some practitioners. While the overall response rate was low, there was no evidence of bias in our sample.
                Copyright (c) 2005 John Wiley & Sons, Ltd. Monetary incentives in survey research may provide important gains from a methodological perspective in the control and reduction of survey error associated with potential nonresponse of participants. However, few studies have systematically investigated the use of monetary incentives or other methods to improve the response rates in the nonphysician clinician population.
                To investigate differences in response rates to a mailed self-administered survey of nonphysician clinicians who were randomized to receive a prepaid monetary incentive, a postsurvey prize drawing, or no incentive.
                A randomized controlled trial of financial incentives was conducted from November 2002 to February 2003. Nonphysician clinicians (nurse practitioners [NPs] and physician assistants [PAs]; N = 3,900) randomly selected to participate in a national ethics-related study were assigned randomly in equal allocations (n = 1,300 [650 NPs, 650 PAs]) to three incentive groups: (a) no incentive; (b) a $5 prepaid token incentive in the initial mailing; or (c) a chance to win one of ten $100 prize drawings upon completion and return of a self-administered survey.
                A $5 cash incentive increased survey response rates to an adjusted 64.2%: a 19.5 percentage point increase over the lottery group (44.7% response rate), and a 22 percentage point increase over the control group (42.2% response rate).
                A nominal cash incentive of $5 yields a significantly higher response rate from nonphysician providers than receiving either a lottery option or no incentive. Although not frequently used in Portugal, postal questionnaires allow the collection of information on patient's follow-up. In this study we assessed the rate of response and the usefulness of a postal questionnaire in a sample of patients with acute stroke. A prospective study was designed and analysed as a case-control: postal questionnaires were sent to 138 patients together with a randomly assigned stamped or post-free return envelope. The percentage of responders was 60% (n=78) and we found no significant differences in response rates according to the mailing strategy (58% for stamped and 62% for post-free return envelopes, p = 0.786). The time gap between hospital discharge and sending of the questionnaire had no significant influence in the response rate. Elder patients and women tend to respond more frequently, but these characteristics also do not change the response rate. Analysing socio-demographic variables reported at the acute phase, we only found differences in response rate for the smoking status: smoking was associated with a lower participation. In conclusion, the present study showed that a postal questionnaire is a useful method for the follow-up of stroke cases and that we must pay special attention to smokers for whom alternative strategies of contact or information should be used to increase compliance with postal questionnaire follow-up. Postal questionnaires are widely used to collect data in healthcare research but a poor response rate may reduce the validity and reliability of results. There was a lack of evidence available relating to use of a monetary incentive to improve the response rate in the healthcare setting.
                The MRC ORACLE Children Study is assessing the health and development of nearly 9000 seven year old children whose mothers' joined the MRC ORACLE Trial. We carried out a randomised controlled trial of inclusion of monetary incentive (five pound voucher redeemable at many high street stores) with the reminder questionnaire to parents. This trial took place between April 2002 and November 2003. When the parents were sent the reminder questionnaire about their child's health and development they were randomly assigned by concealed computer-generated allocation stratified by week of birthday to receive a five pound voucher or no incentive. The population were 722 non-responders to the initial mailing of a 12-page questionnaire. Main outcome measures: Difference in response rate between the two groups.
                Inclusion of the voucher with the reminder questionnaire resulted in a 11.7%(95% CI 4.7% to 18.6%) improvement in the response rate between the two groups.
                This improvement in response rate and hence the validity and reliability of results obtained appears to be justified ethically and financially. Prior research indicates survey procedures that signal significance and individualized mailings have higher response rates. Thus, it was hypothesized that surveys delivered via Priority mail would result in higher return rates than surveys delivered via First-Class. 260 surveys were sent to individuals randomly selected from lists of licensed physical and behavioral healthcare providers in Alaska and New Mexico. Half of the selected individuals were assigned randomly to receive mailings using Priority mail, the other half received First-Class mailings. Return rate was 39% for First-Class and 35% for Priority. Z tests of proportion indicated no statistically significant differences between methods. Given increased costs with no resultant increase in response rate, sending surveys to potential participants via Priority mail does not appear warranted. The authors randomly selected 400 physicians from a population of 1,545 practicing physicians providing follow-up care to patients who received bone marrow or blood stem cell transplants at the Fred Hutchinson Cancer Research Center to determine interest in receiving Internet-based transplant information. In a two-factor completely randomized factorial design, the 400 physicians were assigned to receive mailed surveys with either no compensation or a $5 check and either no follow-up call or a follow-up call 3 weeks after mailing. Overall, 51.5% of the physicians returned the mailed surveys. Comparison of logit models showed that inclusion of a $5 check in the mailer significantly (p = .016) increased the probability of returning the surveys (57.5% vs. 45.5%). In contrast, the telephone follow-up had no overall effect. The authors concluded a modest financial reward can significantly improve physician response rates to research surveys but a telephone follow-up may be inefficient and even ineffective. Although mailed surveys are an important component of epidemiological research, results from mailed surveys are often suspect because of poor response rates and the potential for nonresponse bias. Previous work has demonstrated that paying subjects to complete questionnaires increases response rates, but this work has not well addressed the impact of the timing of incentives on total cost, cost effectiveness, and response bias. We surveyed 400 university employees about health benefits. By random allocation, half received a check for $5 along with the mailed survey, and the other half received the promise of $5 on return of a completed survey. The response rates for both groups were about the same (64 and 59%, respectively), but prepayment was less expensive in aggregate and less expensive per response. In addition, we found that subjects with lower salaries were more likely to respond when paid in advance. We conclude that prepayment may actually be less expensive and more cost effective than payment on completion, but that the timing of payment may influence the profile of respondents. We conducted a pilot study to determine the most efficient mailing strategy for a postal questionnaire study among nurses in Ontario, Canada. Five mailing strategies involving types of stamps on the return envelopes were considered: no stamp, business-reply stamp, metered stamp, small regular stamp, and large commemorative stamp. We found that paper stamps, especially large commemorative stamps, on return envelopes increased the response rate and reduced the response time, as compared with other mailing strategies. Business-reply stamps had the lowest cost per response received and a low total cost. This study assessed efforts to increase response rates to a mailed physician survey and examined whether, as a result, nonresponse bias was reduced.
                Randomly selected physicians and geneticists were mailed a questionnaire concerning genetics knowledge and attitudes. In the final but not the pilot survey, a $25 incentive and intensive follow-up were used to increase the response rate.
                The response rate from physicians in the final survey was 64.8% (n = 1140), compared with 19.6% in the pilot test (n = 69). Sample representatives in sociodemographic and practice characteristics was improved by follow-up. Respondents recruited with more difficulty did not differ on the principal outcome variable, genetics knowledge, except on one subscore. Pilot study and final survey respondents did not differ in knowledge.
                Although the effect of increased response rates on the principal outcome variable in this study was minimal, this may not be the case for other studies. Every effort should be made to attain as high a response rate as is practical and to establish that respondents are representative of the population being sampled. To test alternative response formats for the Nottingham Health Profile (NHP), in terms of acceptability, score distributions, and measurement properties.
                Randomized trial of four response formats for the NHP: original "yes/no" format, a 3-point similarity format ("applies completely/in part/not at all"), a 5-point intensity format ("completely true" to "completely false"), and a 5-point frequency format ("all the time" to "never"). Respondents were patients discharged from a hospital. We compared scores distributions, reliability coefficients, correlations with dimension-specific numerical scales, and patient ratings of the instrument.
                Response rates were similar for the four versions. The original response format had the fewest fully completed questionnaires, and the largest ceiling effects. Internal consistency and test-retest coefficients were acceptable for all versions, but were higher for the two 5-point formats. Correlations reflecting convergent and discriminant validity were higher for the longer response formats than for the original version. The frequency format received the highest ratings from patients, particularly from the sicker and older subgroups.
                The psychometric performance and patient acceptability of the NHP can be improved by using a 5-point frequency response format instead of the original dichotomous response format. The authors examined differences in rate of response, data quality, and cost between mail approaches and in-person interview in the collection of data on sexual history and personal behaviors. A sample of women from a midwestern United States university (n = 342) was identified from health service medical records as having been seen for a sexually transmitted disease (cases) or a contraceptive visit (controls) during the latter half of 1985. The women were randomly assigned to one of three data collection strategies. A total of 268 subjects (78%) participated. Results indicated no differences in validity by method of data collection or by case-control status but there were significant differences in completeness, cost, and response rates. In-person interviews resulted in more complete data than mail approaches, although all instruments had low proportions of missing data (0.001-0.006). Response rate differences were not found when data collection methodologies were compared (75-82%) but were found in case-control analyses. Cases were consistently less likely to participate and significantly less likely to respond by mail (p less than 0.05). The cost of the in-person interview was approximately four times that of the mail survey for the data collection. Implications of the case-control response rate difference suggest that mail methodologies, although low in cost, may introduce sampling bias in studies of sexually transmitted diseases. Improving response rates, particularly among physicians, is important to minimize nonresponder bias and increase the effective sample size in epidemiologic research. We conducted a randomized trial to examine the impact of prepayment vs. postpayment incentives on response rates.
                Self-completion postal questionnaires were mailed to 949 physicians who were respondents to an earlier survey and representative of the general physician population in Hong Kong. These physicians were randomly allocated to receive a HK dollar 20 cash prepayment incentive that accompanied the survey (n=474) or a postpayment reward of the same amount on receipt of the completed questionnaire (n=475).
                The final prepayment response rate was 82.9%, compared with 72.5% in the postpayment arm (P < .001). Of the eight alternative incentive and follow-up strategies evaluated, three lie on the efficiency frontier (i.e., not dominated), including postpayment with three mailings at HK dollar 42.7, prepayment with three mailings at HK dollar 66.5 and prepayment with three mailings and telephone follow-up at HK dollar 112.1 per responder recruited (US dollar 1=HK dollar 7.8).
                The findings demonstrate that prepayment cash incentives are superior to postpayment of the equivalent amount in improving response rates among a representative sample of Hong Kong physicians. Further research should concentrate on confirming the generalizability of these findings in other health care occupation groups and settings. To determine the effect of different methods of administering a diary to collect information from parents on near miss and minor injuries on responses, completeness and accuracy, the number of incidents reported, the effect of a financial incentive on response, and the cost of administering each method.
                The study was set within the context of a cluster randomised controlled trial of injury prevention in 36 practices in Nottingham.
                The study population comprised the 1594 parents who responded to the baseline questionnaire. Parents were allocated systematically to one of four groups: postal administration, with and without financial incentive, telephone administration, with and without financial incentive (102 in each group). A clinic visit method with and without financial incentive (50 in each group) was also used.
                A significant trend was found, with decreasing response rates with increasing degree of contact with the parent, such that administering the diary in the clinic had the lowest response (chi2 for trend = 5.54, 1 df, p = 0.02). Offering a financial incentive increased responses from 47% to 59% (chi2 = 5.78, 1 df, p = 0.016). The most complete recording was found in the diaries handed out at clinic visits. Importantly, parents were accurate in their recording of near miss and minor injuries, suggesting they understood the differences between the two types of incident. Postal methods were the least expensive method of administering the diary in terms of average cost per returned diary. Using a financial incentive resulted in a lower cost per returned diary for telephone and clinic visit methods.
                Parents can accurately and reliably complete diaries recording near miss and minor injuries occurring to their preschool children. More work is needed to investigate methods of increasing response. Postal diaries achieve the highest response but have the least complete recording of data. Diaries administered through child health clinics were most complete but achieved the lowest response. The administration method chosen in future work should be influenced both by the response and completeness of recording that is required by the research. The objective of this study was to compare the impact of closed- versus open-ended question formats on the completeness and accuracy of demographic data collected in a mailed survey questionnaire. We surveyed general internists in five Canadian provinces to determine their career satisfaction. We randomized respondents to receive versions of the questionnaire in which 16 demographic questions were presented in a closed-ended or open-ended format. Two questions required respondents to make a relatively simple computation (ensuring that three or four categories of response added to 100%). The response rate was 1007/1192 physicians (80.0%). The proportion of respondents with no missing data for all 16 questions was 44.7% for open-ended and 67.0% for closed-ended formats (P < 0.001). The odds of having missing items remained higher for open-ended response options after adjusting for a number of respondent characteristics (2.67, 95% confidence interval 2.01 to 3.55). For the two questions requiring computations focused on professional activity and income, there were more missing data (P = 0.02, 0.02, respectively) but fewer inaccurate responses (P = 0.009, 0.20, respectively) for the open-ended compared to the closed-ended format. Investigators can achieve higher response rates for demographic items using closed format response options, but at the risk of increasing inaccuracy in response to questions requiring computation. nan It is becoming increasingly difficult to obtain high response rates in physicians' mail surveys. In 1983-84, we tested the effectiveness of two techniques among 604 Quebec physicians who had not responded to an initial letter. A handwritten thank you note at the bottom of the letter accompanying the questionnaire and a more personalized mailout package increased response rates by 40.7 per cent and 53.1 per cent, respectively, compared to control groups. To assess the impact of patient satisfaction survey method on response rate, data quality and satisfaction.
                Four modes of data collection were assessed during a randomized trial that included 400 inpatients discharged from a teaching hospital.
                The response rate was 58% within the mail survey group (72% with follow-up letter) versus 73% and 81% within the home and telephone interview group (p < 0.01). 69% of the mailed questionnaires contained no missing values versus 94% and 96% for home and telephone interview modes (p < 0.01). The global satisfaction scale score was greater within the mail survey groups (8.1/10 without follow-up letter and 7.9 with follow-up letter) than within the telephone interview group (7.8) and the face to face interview group (7.3), (p < 0.05).
                Mail survey with follow-up letter constitutes an operational method despite lower data quality and overestimation of patients' satisfaction scores. The validity of the results of mailed surveys is often threatened by nonresponse bias, which is made more likely when response rates are low. However, the effectiveness and cost-effectiveness of several strategies to increase response rates are uncertain.
                To assess three strategies to increase response rates to mailed physician surveys: including a 10 dollars versus a 5 dollars cash incentive in the initial mailing, including a mint candy or not, and using a large versus small outgoing envelope.
                Using a 2 x 2 x 2 factorial design, a randomized trial of these strategies was conducted in a survey of 1200 physicians randomly selected from the American Medical Association's Master File.
                Including a 10 dollars incentive yielded a significantly higher response rate (60.5% vs. 52.8%) (P = 0.009). The mailing and incentive costs per completed response were 12.24 dollars (95% CI, 11.75 dollars, 13.64 dollars) in the 5 dollars group and 18.48 dollars (95% CI, 17.77 dollars, 20.69 dollars) in the 10 dollars group. Each additional response obtained in the 10 dollars group came at an incremental cost of 61.26 dollars (95% CI, 36.98 dollars, 200.80 dollars). Neither inclusion of a mint nor use of a large envelope influenced the response rate.
                Investigators may increase response rates by including more money in the initial questionnaire packet, but there may be diminishing returns to serial increments in incentives greater than 5 dollars. Including smaller incentives in more questionnaires may maximize total responses. To study the effect of a lottery incentive on questionnaire response rate.
                In Copenhagen County, Denmark, a random sample of 2543 men and women between the ages of 19 and 60 were randomised into a control group and an intervention group. Both groups were contacted by mail and asked to complete a questionnaire on sociodemografic characteristics, self-rated health and self-reported physical activity level. The intervention group was offered participation in a small lottery for returning the questionnaire. No incentive was offered to the control group.
                The final response rate for the control group was 60.4 and 63.4% for the intervention group. Although the response rate was significantly higher in the intervention group after 2 and 3 weeks, the difference in the final response rate between groups was not statistically significant (p = 0.12). There was no statistically significant difference between groups in sociodemografic characteristics, self-rated health or self-reported physical activity level.
                A lottery incentive had no significant effect on the overall response rate, but may have contributed to a quicker response. Furthermore a lottery incentive did not seem to alter the selection of respondents. There is substantial interest in use of the Internet for surveys, but there have been few health-oriented, large, randomized trials of general population surveys on the Internet. It is unclear whether providing the option to respond via Internet increases the response rate, and to what degree the results will differ.
                The aim of the study was to evaluate changes in response rate and outcomes in a postal respiratory health survey by adding an optional Web response alternative.
                This was a randomized trial of a random sample of 4213 permanent residents of Norway, aged 20-40 years. Participants were randomized into a traditional survey arm, where they were asked to return the survey by mail, and an arm where they were also offered the option to respond via a Web form.
                A total of 1928/4213 subjects responded, a response rate of 45.8% across both arms. The total response rate was 44.8% (944/2105) in the postal plus optional Internet response arm and 46.7% (984/2108) in the usual postal survey arm, with no statistically significant difference between the randomized groups (P = .24). In the optional Internet arm, 8.3% (175/2105) of the sample responded using the Internet and 36.5% (769/2105) responded by post. Thus, Internet response was chosen by 18.5% (175/944) of those who replied in the optional Internet arm. In the multivariate analysis, Internet response was associated with being male, frequency and type of Internet access (home users more likely to respond by Internet than work users), and smoking habit, with current smokers being more likely to be Internet responders. 57% preferred postal response (1102/1928), 38% preferred Internet response (733/1928), and 3% preferred telephone interview (54/1928), with no difference between randomization arms (P = .56). But among those who indicated that they preferred the Internet response and who were randomized to the optional Internet arm, only 47% actually chose the Internet response. Asthma prevalence was higher among participants choosing the Internet response mode (16.7% vs 12.4%).
                We failed to increase survey response rates by adding an optional Internet response. Asthma diagnosis was higher in the Internet response group, suggesting nonresponse bias. Method comparison studies should be carried out before Internet studies are accepted in new populations or new subject matters. Studies largely from the market research field suggest that the inclusion of a stamped addressed envelope, rather than a pre-paid business reply, increases the response rate to mail surveys. The evidence that this is also the case regarding patient mail surveys is limited.
                The aim of this study is to investigate whether stamped addressed envelopes increase response rates to patient mail surveys compared to pre-paid business reply envelopes and compare the relative costs. A sample of 477 initial non-responders to a mail survey of patients attending breast clinics in Greater Manchester between 1/10/2002 - 31/7/2003 were entered into the trial: 239 were randomly allocated to receive a stamped envelope and 238 to receive a pre-paid envelope in with their reminder surveys. Overall cost and per item returned were calculated.
                The response to the stamped envelope group was 31.8% (95% CI: 25.9% - 37.7%) compared to 26.9% (21.3% - 32.5%) for the pre-paid group. The difference (4.9% 95% CI: -3.3% - 13.1%) is not significant at alpha = 0.05 (chi2 = 1.39; 2 tailed test, d.f. = 1; P = 0.239). The stamped envelopes were cheaper in terms of cost per returned item (1.20 pounds) than the pre-paid envelopes (1.67 pounds). However if the set up cost for the licence to use the pre-paid service is excluded, the cost of the stamped envelopes is more expensive than pre-paid returns (1.20 pounds versus 0.73 pounds).
                Compared with pre-paid business replies, stamped envelopes did not produce a statistically significant increase in response rate to this patient survey. However, the response gain of the stamped strategy (4.9%) is similar to that demonstrated in a Cochrane review (5.3%) of strategies to increase response to general mail surveys. Further studies and meta analyses of patient responses to mail surveys via stamped versus pre-paid envelopes are needed with sufficient power to detect response gains of this magnitude in a patient population. To determine the degree to which mailed survey response rates, response times, and nonresponse bias are affected by questionnaire size and color.
                Questionnaires were mailed to a random sample of 2,000 Mayo Clinic patients in one of four size/color "test" groups. One thousand three hundred nine surveys were completed, approximately two-thirds in each group.
                A small (6 (1/8) x 8 (1/4) in) questionnaire booklet on white paper had a higher response rate (68.4%) than a similarly sized questionnaire on blue paper (62.3%). A large (8 (1/4) x 11 in) questionnaire on white paper had a 62.7% rate, whereas a large, blue questionnaire had a response rate of 68.6%. Median response times did not differ by questionnaire size/color. No evidence of differential nonresponse bias was observed across the four test groups.
                This study supports the use of a small/white questionnaire format advocated by the Total Design Method advanced by Don Dillman at Washington State University. We observed a favorable response rate for a large questionnaire printed on blue paper; however, if time and resources are limited, use of a small/white questionnaire appears preferable. nan A systematic review identified a range of methods, which can influence response rates. However, analysis specific to a healthcare setting, and in particular, involving people expected to be poor responders, was missing, We examined the effect of pre-warning letters on response rates to a postal survey of sedentary patients whom we expected a low rate of response.
                Participants were randomised to receive a pre-warning letter or no pre-warning letter, seven days before sending the main questionnaire. The main questionnaire included a covering letter and pre-paid return envelope. After seven days, non-responders were sent a reminder letter and seven days later, another reminder letter with a further copy of the questionnaire and return envelope.
                627 adults, with a mean age of 48 years (SD 13, range 18 to 78) of whom 69.2% (434/627) were women, were randomised. 49.0% (307/627) of patients were allocated to receive a pre-warning letter and 51.0% (320/627) no pre-warning letter, seven days in advance of posting the main questionnaire. The final response rate to the main questionnaire was 30.0% (92/307) amongst those sent a pre-warning letter and 20.9% (67/320) not sent a pre-warning letter, with an adjusted odds ratio of 1.60 (95% CI 1.1, 2.30).
                The relatively low cost method of sending a pre-warning letter had a modest impact on increasing response rates to a postal questionnaire sent to a group of patients for whom a low response rate was anticipated. Investigators should consider incorporating this simple intervention when conducting postal surveys, to reduce the potential for nonresponse bias and to increase the study power. Methods other than postal surveys may be needed however when a low response rate to postal surveys is likely. To assess whether changing the layout of the SF-12 affected item response rates, we tested two SF-12 formats in a quasi-randomized trial of women aged >or=70 years in two general practices in North Yorkshire. The modified version of the SF-12 ('York SF-12') converted the 'stem and leaf' format of some questions to individual items. We assessed the effect of the two types of questionnaires on item response rates. The difference in overall response rates to the two questionnaires (York SF-12 26.8%; SF-12 29.5%) was not statistically significant (95%CI -1.88% to 7.22%). However, the modified SF-12 had a statistically significantly lower item non-response rate of 8.5%, compared with the 26.6% of the SF-12 (95%CI 11.1%-25.1%). Chronbach's alpha reliability scores for the York SF-12 were also slightly better than for the older version. The York version of the SF-12 is an improvement on the original questionnaire. We recommend that the York SF-12 be used in preference to the SF-12 when surveying an older population. Achieving acceptable response rates from health care providers via postal questionnaires is an ongoing challenge. The use of monetary incentives is one of the most effective strategies for increasing response rates. However, the effect and cost of such an incentive on retail pharmacists' response rates has not been well studied.
                A sample of 700 pharmacies was selected at random from the electronic Yellow Pages in NSW Australia and mailed a brief survey regarding pharmacotherapies and advice for smoking cessation. Half of the sample was randomly allocated to receive an offer of an 14 US dollars gift voucher.
                The response rates were 65.9% for the voucher group and 53.5% for the no-voucher group. The odds of response from the voucher group was 1.68 (95%CI = 1.23, 2.30) times greater than for the no-voucher group. The cost per additional respondent was 67.95 US dollars. The incentive also reduced follow up costs by 10%.
                A moderately sized monetary incentive is able to achieve a significant increase in response rates for retail pharmacists, thereby reducing potential bias in the sample. Response rates to postal questionnaires are falling and this threatens the external validity of survey findings. We wanted to establish whether the incentive of being entered into a prize draw to win a personal digital assistant (PDA) would increase the response rate for a national survey of consultant obstetricians and gynaecologists.
                A randomised controlled trial was conducted. This involved sending a postal questionnaire to all Consultant Obstetricians and Gynaecologists in the United Kingdom. Recipients were randomised to receiving a questionnaire offering a prize draw incentive (on response) or no such incentive.
                The response rate for recipients offered the prize incentive was 64% (461/716) and 62% (429/694) in the no incentive group (relative rate of response 1.04, 95% CI 0.96 - 1.13)
                The offer of a prize draw incentive to win a PDA did not significantly increase response rates to a national questionnaire survey of consultant obstetricians and gynaecologists. The effects of incentive size on physicians' response rates to a mail survey were determined.
                One thousand US primary care physicians were assigned randomly to receive a survey with either a $5 bill or a $2 bill as an incentive. For each of the two incentive groups, the overall response rate for three mailing waves, the total cost, and the total cost per usable response were measured.
                The response rate among those receiving the $5 bill (61%) was 32% higher than the response rate among those receiving the $2 bill (46%); overall costs were slightly higher in the $5 group, but the cost per response for each group was similar ($15.46 versus $14.93). For the same cost, a higher response rate could have been achieved in the $2 group if costs saved from foregoing the third mailing were instead used to increase the incentive for a portion of the subjects.
                A $5 bill incentive yielded a higher response rate among the physicians in this study than did a $2 bill incentive. Moreover, the powerful effect of the incentive size, combined with the consequent decline in the costs of subsequent mailing waves, suggests that resources in a fixed survey budget are allocated more efficiently to increasing the initial incentive rather than to providing a third wave to nonresponders. In a survey about euthanasia, 1,600 critical care nurses were randomly assigned to receive either three complete, anonymous mailings of the questionnaire or, with each mailing, a coded postcard to be returned separately from the questionnaire to reduce subsequent mailings to previous responders. The response rate in these two groups was 76.5% [95% confidence interval (CI) = 73.6-79.4%] and 69% (95% CI = 65.7-72.4%), respectively. The two strategies yielded similar responses, and costs were much lower for the postcard group. Using coded postcards to be returned separately from completed instruments appears to lower the response rate to anonymous mail surveys, but it also lowers cost and may not introduce additional bias. Effective strategies to maximize response rates to self-administered surveys of clinicians are crucial to minimize response bias. Offers of charitable donations have been assessed for their potential to promote participation of community samples but not in the context of medical specialist samples. We randomized all Australian colorectal surgeons (n = 219) to whom we mailed a survey about clinical practice guidelines to receive either a standard covering letter or one promising a donation to their peak professional organization upon our receipt of their completed survey. Contrary to expectations, surgeons advised that their participation would secure a donation to their college were significantly less likely to return their questionnaire (84.3%, 95% CI 76.0-90.5%) than those receiving a standard letter (93.7%, 95% CI 87.4-97.4%). They also were more tardy in their response (Hazard Ratio = 0.75, 95% CI 0.57-1.00) (P = 0.047). In this context, offering donations to surgeons was counterproductive in enhancing response rates. Self-administered questionnaires are commonly used in experimental studies to elicit quality of life or other outcomes. Hence, achieving an acceptable level of follow-up from patients is critical to minimizing bias. Many methods for maximizing follow-up remain untested. It is also unclear what level of follow-up is required to prevent bias being introduced.
                We recruited 246 men from general practice surgeries in Sydney, Australia. These 246 men were randomized to receive a covering letter with their follow-up questionnaire either advising of a deadline to reply (Deadline, n = 126) or a standard letter without a deadline (No Deadline, n = 120). Four standardized reminder prompts subsequently were administered. We calculated interim response rates and the final proportion of follow-up questionnaires received according to group. We also compared scores on two main outcomes, namely, knowledge and decisional conflict at each time when reminder prompts were administered.
                One hundred and twelve (88.9%) men in the Deadline group returned their follow-up questionnaires compared with 102 (85.0%) men in the No Deadline group. This difference was not statistically significant [odds ratio = 1.41, 95% confidence interval (CI) = 0.67-2.99; p = 0.36]. Time to response also was not significantly affected by cover letter received (hazard ratio = 0.96; 95% CI = 0.73-1.25; p = 0.76). Results of the original RCT were similar in terms of direction and effect size at all times irrespective of when reminder prompts were administered.
                The addition of a deadline adds no further impact in improving response rates from male patients compared with an unspecified letter. Despite the accepted wisdom that higher response protects against bias, differences in outcomes were consistent throughout the post-test data collection period. The purpose was to determine whether asking about ethnic origin and housing tenure in a postal survey affects the response rate.
                The study derived from a postal survey designed to determine eligibility for a study of outpatients. A two way factorial design was used to look at the two experimental factors, questionnaires being randomly divided into four groups with or without questions about ethnic origin and housing tenure.
                10,000 people (1000 from each of 10 areas) were systematically sampled from electoral registers, the areas being chosen to give a nationally representative sample.
                The response rate was 66% irrespective of whether ethnic origin was asked about, but was 65% and 67% respectively to questionnaires with and without questions about housing tenure.
                Asking about ethnic origin did not affect the overall response to this survey although it is possible that the response from some ethnic minority groups was lower. Asking about housing tenure slightly, but significantly, decreased response. In this study, the authors sought to determine the effects of length and clarity on response rates and data quality for two food frequency questionnaires (FFQs): the newly developed 36-page Diet History Questionnaire (DHQ), designed to be cognitively easier for respondents, and a 16-page FFQ developed earlier for the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. The PLCO Trial is a 23-year randomized controlled clinical trial begun in 1992. The sample for this substudy, which was conducted from January to April of 1998, consisted of 900 control and 450 screened PLCO participants aged 55-74 years. Controls received either the DHQ or the PLCO FFQ by mail. Screenees, who had previously completed the PLCO FFQ at baseline, were administered the DHQ. Among controls, the response rate for both FFQs was 82%. Average amounts of time needed by controls to complete the DHQ and the PLCO FFQ were 68 minutes and 39 minutes, respectively. Percentages of missing or uninterpretable responses were similar between instruments for questions on frequency of intake but were approximately 3 and 9 percentage points lower (p < or = 0.001) in the DHQ for questions on portion size and use of vitamin/mineral supplements, respectively. Among screenees, response rates for the DHQ and the PLCO FFQ were 84% and 89%, respectively, and analyses of questions on portion size and supplement use showed few differences. These data indicated that the shorter FFQ was not better from the perspective of response rate and data quality, and that clarity and ease of administration may compensate for questionnaire length. Young adults who had previously participated in a longitudinal survey of youth were sent a questionnaire. They were randomly assigned to receive a $20 prepayment, a $20 postpayment, or a $25 postpayment for participation in the latest survey. Those in the large incentive condition were 7 percentage points more likely to return a survey than those in the smaller, postpayment group. Prepayment had a smaller, less reliable effect. Effects of incentive magnitude and timing were consistent at each month of the study period; only better high school grades distinguished early responders from late responders. Nonresponders had characteristics suggestive of low social conformity and were more likely than responders to be African American and male and have low SES. The discussion centers on motivations for participating in research and differences in the incentives likely to promote continued response versus initial study enrollment. A range of factors have been shown to affect the response rate to mailed questionnaires, but particular strategies to improve patients' response in trials conducted in general practice require further study.
                Non-responders in a larger trial were randomized to receive a telephone or recorded delivery reminder on the third contact. The cost of administration of each method was estimated.
                Significantly more patients returned completed questionnaires when sent questionnaires by recorded delivery, although the cost per patient contacted was nearly three times more than for contact by telephone.
                Our study indicates that sending reminders by recorded delivery, although more expensive, is more effective than telephone reminders for recruiting patients to a study in general practice using research questionnaires. The purpose of this study was to assess the impact of sponsorship of a mailed satisfaction survey on response patterns and patient satisfaction ratings, and to establish whether satisfaction ratings depend on the timing of response. The study was part of a patient satisfaction survey conducted in a medical group practice in Geneva, Switzerland. All persons who had received an outpatient visit at the medical practice in the last week of September 1993 were assigned randomly to receiving the survey package either on university letterhead or on the medical practice letterhead. Participation rates were 80.5% and 80.4% in the two groups, respectively. The sponsorship of the survey had no detectable impact on response speed or response completeness. Six out of seven satisfaction scores were higher in the "medical practice" group, but the differences were not statistically significant. As data collection progressed, the cumulative satisfaction rating decreased gradually. This association was statistically significant but moderate. Whether a satisfaction survey is sponsored by a university or a health care provider does not seem to affect survey results. However, low survey response rates may moderately bias satisfaction estimates toward higher values. Twins taking part in two unrelated studies were sent a questionnaire together with a self-addressed envelope that either carried one or multiple (up to 5) stamps to the same value. The unprompted proportion of questionnaires returned (before commencement of telephone reminder calls) was increased from 62% to 71% in one study, and from 43% to 52% in the other study (test for common odds ratio in studies, p = 0.04). Response rates to surveys are declining and this threatens the validity and generalisability of their findings. We wanted to determine whether paper quality influences the response rate to postal surveys
                A postal questionnaire was sent to all members of the British Society of Gynaecological Endoscopy (BSGE). Recipients were randomised to receiving the questionnaire printed on standard quality paper or high quality paper.
                The response rate for the recipients of high quality paper was 43/195 (22%) and 57/194 (29%) for standard quality paper (relative rate of response 0.75, 95% CI 0.33-1.05, p = 0.1
                The use of high quality paper did not increase response rates to a questionnaire survey of gynaecologists affiliated to an endoscopic society.
Health researchers using postal and electronic questionnaires can increase response using the strategies shown to be effective in this systematic review.