Take Tobacco case as an example, the interviewer must have known whether they had cancer or not, which is likely to affect their recollection. 

University of Michigan - Ann Arbor

Recall bias is a error that occurs when participants do not remember previous events or experiences accurately or omit details: the accuracy and volume of memories may be influenced by subsequent events and experiences.

Recall Bias

Pearl, J., & Mackenzie, D. (2018). $\mathit{The \ Book \ of \ Why: \ The \ New \ Science \ of \ Cause \ and \ Effect.}$ Basic Books.

The Book of Why

Recall bias usually occurs in studies which involve self-reporting, such as case-control studies and retrospective cohort studies.

Types of Studies where Recall bias happens

- Can potentially exaggerate the relation between a potential risk factor and the disease.
- Might not remove factors which may not be correalted

Major Problems with recall bias

Wash out period:
            a certain fixed time period that must elapse between the subject's first observation and their subsequent observation of the same event.

How to Account for recall bias

A patient being treated for ADHD might remember certain large events in time of panic or neglect small gradual changes

A trial of cancer patients not sharing family history

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