Asking questions changes health-related behaviour: An updated systematic review and meta-analysis

Lisa M Miles, Angela M Rodrigues, Falko F Sniehotta, David P French

Research output: Contribution to journalReview articlepeer-review


OBJECTIVE: The question-behaviour effect refers to whether asking people questions can result in changes in behaviour. Such changes in behaviour can lead to bias in trials. This study aims to update a systematic review of randomised controlled trials investigating the question-behaviour effect, in light of several large pre-registered studies being published.

STUDY DESIGN AND SETTING: A systematic search for newly published trials covered 2012 to July 2018. Eligible trials randomly allocated participants to measurement versus non-measurement control conditions or to different forms of measurement. Studies that reported health-related behaviour as outcomes were included.

RESULTS: Forty-three studies (33 studies from the original systematic review and 10 new studies) compared measurement versus no-measurement. An overall small effect was found using a random effect model: SMD = 0.06 (95% CI 0.02-0.09), n= 104,388. Statistical heterogeneity was substantial (I2 =54%). In an analysis restricted to studies with a low risk of bias, the QBE remained small but significant. There was positive evidence of publication bias.

CONCLUSION: This update shows a small but significant question-behaviour effect in trials with health-related outcomes, but with considerable unexplained heterogeneity. Future trials are needed with lower risk of bias are needed, with pre-registered protocols and greater attention to blinding.

Original languageEnglish
Pages (from-to)59-68
JournalJournal of Clinical Epidemiology
Early online date27 Mar 2020
Publication statusPublished - 30 Mar 2020


  • question-behaviour effect
  • bias
  • measurement reactivity
  • randomised control trial
  • behaviour


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