PEARLS 20, September 2007, written by Brian R McAvoy

Clinical question
How can response rates to postal questionnaires be increased?

Bottom line
Response rates to postal questionnaires can be increased by contacting people before they are sent the questionnaire.Questionnaires and letters should be made personal, kept short, and a stamped return envelope provided. Incentives should be offered (preferably a small amount of money). One or more reminders should be sent with a copy of the questionnaire to people who do not reply.

Caveat
The odds of response were reduced when the questionnaire included questions of a sensitive nature, when questionnaires began with the most general questions or when participants were offered an opportunity to opt out of the study.

Context
Postal questionnaires are widely used for data collection in studies but non response can reduce effective sample size and introduce bias. Finding ways of increasing response rates would improve the quality of health research.

Cochrane Systematic Review
Edwards P, Roberts I, Clarke M et al. Methods to increase response rates to postal questionnaires. Cochrane Database of Systematic Reviews 2007, Issue 2. Article No. MR000008. DOI: 10.1002/14651858.MR000008.pub3.