Evidence-appraisal glossary
Recall bias
Recall bias is a systematic error that occurs when the accuracy or completeness of participants' memories differs between the groups being compared. It is most damaging in case-control and other studies that ask people to remember past exposures.
Also called: recall error, reporting recall bias.
Recall bias is common when people with a disease search their history for explanations and so report exposures more thoroughly than healthy comparisons. Because the distortion differs between groups, it can manufacture an apparent link between an exposure and an outcome that is not real, or mask a true one. It is not simply forgetting; the problem is that forgetting or over-reporting is unequal across the groups.
This is a plain-language methodology definition for reading research. It is general education, not medical advice.