Population
cognitive impairment, a disability, acute illness
The sample size was calculated using a formula by Vaughan et al.The following subjects were eligible for this study: (1) Chiang Mai Province residents aged 25–50 years (as of September 30th, 2020) with Thai nationality according to the civil registration; (2) the participants must have lived in their own residence for at least 1 year before the data collection date; (3) be able to read and write Thai; and (4) be able to provide informed consent. The subjects who presented with a disability, acute illness, or cognitive impairment, or who had been unemployed for more than 1 year before taking the questionnaire were excluded.A stratified multistage random sampling technique was performed to recruit the subjects in Chiang Mai Province, Thailand. To begin, all districts in Chiang Mai Province were classified into 5 groups based on their geographic locations and the Chiang Mai Province’s patient referral system. Next, a quota sampling technique was used to select the districts based on the population ratios among groups. All districts in groups 1 and 2 were selected. For groups 3–5, two districts per group were randomly selected. As a result, 16 out of 25 districts in Chiang Mai Province were selected. For each selected district, 2–4 subdistricts were purposely selected. The accidental sampling method was used to select subjects from the general Thai population who met the eligibility criteria. Required and actual samples for each selected district are presented in Table 