A randomized trial found online questionnaires supplemented by postal reminders generated a cost-effective and generalizable sample but don't forget the reminders.

OBJECTIVES

The objective of this study was to compare the response rates, data completeness, and representativeness of survey data produced by online and postal surveys.

STUDY DESIGN AND SETTING

A randomized trial nested within a cohort study in Yorkshire, United Kingdom. Participants were randomized to receive either an electronic (online) survey questionnaire with paper reminder (N = 2,982) or paper questionnaire with electronic reminder (N = 2,855).

RESULTS

Response rates were similar for electronic contact and postal contacts (50.9% vs. 49.7%, difference = 1.2%, 95% confidence interval: -1.3% to 3.8%). The characteristics of those responding to the two groups were similar. Participants nevertheless demonstrated an overwhelming preference for postal questionnaires, with the majority responding by post in both groups.

CONCLUSION

Online survey questionnaire systems need to be supplemented with a postal reminder to achieve acceptable uptake, but doing so provides a similar response rate and case mix when compared to postal questionnaires alone. For large surveys, online survey systems may be cost saving.