What is the definition of recall bias?

Recall bias is defined as a systematic difference in the accuracy or completeness of the recollections retrieved by study participants regarding past events or exposures. In epidemiological studies, particularly retrospective ones, participants may not remember past exposures accurately, leading to a distortion in the findings. This can occur when individuals with a specific outcome, such as a disease, might remember past exposures differently compared to those without the disease.

For instance, if a study is investigating the link between a certain lifestyle factor and a health condition, individuals with the health condition might be more likely to recall and report past exposure to that factor than those who are healthy. This can result in an overestimation or underestimation of the association between the exposure and the outcome, thus impacting the study's validity.

Other options refer to different biases and errors in research methodology. Systematic deviation of results refers to a broader category of errors without the specific focus on memory recall associated with exposure. Bias introduced by surveillance methods involves how data is gathered and can lead to different forms of bias but does not specifically address the memory of exposures. Choosing unrepresentative samples pertains to sampling bias, where the sample does not adequately reflect the population of interest, but again, this is not about recall. Each of these options