Recall bias — MRCPsych Paper A MCQ

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ModerateEpidemiology and research methodsRecall biasMRCPsych Paper A

A case-control study examines whether childhood adversity is associated with psychosis. Cases with established psychosis and controls without psychosis are interviewed using the same retrospective questionnaire. Contemporaneous health and safeguarding records indicate similar recorded rates of adversity in the two groups, but cases report substantially more adversity during interview. Which bias most likely accounts for this discrepancy?

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Correct answer: B — Recall bias

The correct answer is B, recall bias. This is differential misclassification of a past exposure: knowledge or experience of the outcome may cause cases to search their memories more intensively, or report adversity differently, than controls. The discrepancy between retrospective reports and comparable contemporaneous records is the key discriminator. Attrition bias results from systematic differences between participants who remain in a study and those lost to follow-up. Lead-time bias concerns apparently prolonged survival caused by earlier diagnosis. Spectrum bias occurs when diagnostic-test performance varies across different patient or disease spectra. The healthy worker effect arises when employed populations appear healthier than the general population because people with significant illness are less likely to enter or remain in employment.

Reference: Tenny S, Kerndt CC, Hoffman MR. Case Control Studies, section 'Disadvantages and Limitations'. StatPearls [Internet], 2026 edition. https://pubmed.ncbi.nlm.nih.gov/28846237/