Recall Bias
Reporting Bias
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. For example, in studies of risk factors for cancer, people who have had the disease may search their memories more thoroughly than members of the unaffected control group.
Origin
The concept emerged from fundamental limitations of human memory in epidemiological research, particularly in case-control studies and retrospective cohort designs. The exact origin is uncertain, though the concern became prominent in mid-20th-century epidemiology as researchers recognized that participants relying on memory to identify past exposures produce systematically biased data. Factors affecting recall accuracy include age, education, socioeconomic status, the importance of the condition to the patient, time interval since the event, and whether the study participant has poorer recall generally. Recall bias is commonly believed to be "pervasive in case-control studies," where cases may search memories more thoroughly than controls.