What is information bias from recall?

• A. Misclassification of outcome due to inaccurate memory.
• B. Bias due to interviewer effects.
• C. Misclassification of exposure due to inaccurate memory.
• D. Loss to follow-up bias.

Answer: (C)

Recall bias is a form of information bias that happens when exposure information relies on participants’ memory and those memories are imperfect or different between groups. In studies that look back in time, especially case-control studies, cases may remember past exposures more clearly or emphasize them differently than controls. This leads to misclassification of whether someone was exposed, which can distort the observed association between exposure and outcome. So, information bias from recall is misclassification of exposure due to inaccurate memory.

Other biases listed are different in origin: interviewer effects are about how questions are asked, loss to follow-up is about attrition, and misclassification of outcome due to inaccurate memory would be recall for outcome data rather than exposure data.