Nonprobability Web surveys to measure sexual behaviors and attitudes in the general population: a comparison with a probability sample interview survey.
Bob ErensSarah M BurkillMick P CouperFrederick ConradSoazig CliftonClare TantonAndrew PhelpsJessica DattaCatherine H MercerPam SonnenbergPhilip PrahKirstin Rebecca MitchellKaye WellingsAnne M JohnsonAndrew J CopasPublished in: Journal of medical Internet research (2014)
Consistent with studies from other countries on less sensitive topics, volunteer Web panels provided appreciably biased estimates. The differences seen with Natsal-3 CASI questions, where mode effects may be similar, suggest a selection bias in the Web surveys. The use of more complex quotas may lead to some improvement, but many estimates are still likely to differ. Volunteer Web panels are not recommended if accurate prevalence estimates for the general population are a key objective.