Recall bias

In epidemiological research, recall bias is a systematic error caused by differences in the accuracy or completeness of the recollections retrieved ("recalled") by study participants regarding events or experiences from the past.^[1] Sometimes also referred to as response bias, responder bias or reporting bias, this type of measurement bias can be a methodological issue in research involving interviews or questionnaires, in which case it could lead to misclassification of various types of exposure.^[2] Recall bias is of particular concern in retrospective studies that use a case-control design to investigate the etiology of a disease or psychiatric condition.^[3] For example, in studies of risk factors for breast cancer, women who have had the disease may search their memories more thoroughly than members of the unaffected control group; those who had the disease may recall a greater variety of risk factors they had been exposed to, including those falsely attributed to the disease in the media, such as use of oral contraceptives.^[4] To minimize recall bias, some clinical trials have adopted a "wash out period", i.e., a substantial time period that must elapse between the subject's first observation and their subsequent observation of the same event.^[5]

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