Background
NMS
NMS, SECONDARY
Surveys are an important method for collecting health-related data, particularly data which are not routinely available from other sources. Population-based surveys often use random sampling to select respondents and employ a variety of data collection methods, such as structured interviews or questionnaires administered via post or online. Irrespective of the methodology, there has been a steady decline in response rates to surveys over recent decades [Surveys with low response rates are less likely to be representative of their target population [Since the early 2000s there has been a rapid increase in online surveys recruiting through social media and often with no sampling frame [Bias due to non-response can be mitigated to some extent by applying correction techniques such as survey weighting, whereby the sample is weighted on certain characteristics in order to more accurately reflect the target population [The 2020 NMS included an RCT (with standard paper and push-to-web survey arms) and a concurrent social media survey. The primary objective (of the RCT only) was to compare response rates between the paper survey and the push-to-web survey. The secondary objectives were to compare the paper survey, push-to-web survey and social media survey with respect to: respondent representativeness; external validity of prevalence estimates of key maternity indicators (compared with the same indicators in national routine data); and financial costs.