Which study design is MOST impacted by recall bias?

Correct answer: B. Case-control study

• A. Incorrect. RCTs are prospective and randomized — exposure and outcomes are tracked forward in time, not recalled after the fact.
• B. Correct. Case-control studies are MOST prone to RECALL BIAS. Cases (with disease) and controls (without) are asked to recall PAST EXPOSURES. Cases are more likely to remember and report exposures because they seek explanations for their disease — causing systematic differential recall.
• C. Incorrect. Cohort studies are prospective — exposure status is determined before outcomes develop.
• D. Incorrect. Cross-sectional studies assess exposure and outcome simultaneously, with less retrospective recall bias than case-control.