Citation

Kypri K, Samaranayaka A, Connor J, Langley JD, Maclennan B. Prev. Med. 2011; 53(4-5): 274-277.

Affiliation

Centre for Clinical Epidemiology & Biostatistics, School of Medicine and Public Health, University of Newcastle, Callghan, NSW 2308, Australia; Injury Prevention Research Unit, Department of Preventive & Social Medicine, University of Otago, Dunedin, New Zealand.

Copyright

(Copyright © 2011, Elsevier Publishing)

DOI

10.1016/j.ypmed.2011.07.017

PMID

21827781

Abstract

OBJECTIVE: There has been little investigation of non-response bias in web-based health surveys. We hypothesised that non-respondents have a higher prevalence of risk behaviours than respondents. METHOD: In 2005, random sample of students aged 17-25years from 12 New Zealand tertiary institutions (n=7130) were invited to complete a web-based health behaviour survey, with three e-mail reminders. Early respondents (before 2nd reminder) were compared with late respondents (after 2nd reminder). Late respondents served as a proxy for non-respondents. RESULTS: 2607 students (37%) responded early, 676 (9%) responded late, and 3847 (54%) did not respond. There were differences between early and late respondents in high school binge drinking (38% vs 47%, p=0.002) and non-compliance with physical activity guidelines (12% vs 18%, p=0.004). Differences in overweight/obesity (26% vs 31%, p=0.058), smoking (18% vs 22%, p=0.091) and non-compliance with dietary guidelines (76% vs 77%, p=0.651) were non-significant but point estimates were in the expected direction. Estimated bias in prevalence of risk behaviours was an absolute difference of 1-4% and a relative difference of 0-21%. CONCLUSION: Respondents whose participation was hardest to elicit reported more risk behaviour. Assuming non-respondents' behaviour is similar or more extreme than that of late respondents, prevalence will have been substantially underestimated.

Language: en