Background: Monitoring health targets is often undertaken using questionnaire surveys of lifestyle risk factors. Non-response bias is recognized but rarely quantified.
Methods: Following a questionnaire survey on a random sample of 6009 residents of Somerset with a response rate of 57.6 per cent, a telephone survey was undertaken on a random sample of 400 non-responders. A small number of the more important questions from the questionnaire were put to the non-responders over the phone.
Results: Fifty-nine per cent of the sample were contacted and agreed to participate. Statistically significant differences between responders and non-responders to the original questionnaire were detected for current smoking, hazardous alcohol consumption and lack of moderate or vigorous activity.
Conclusions: Lifestyle questionnaire surveys need to include an assessment of the non-response bias.