Which types of studies are subject to recall bias?

Recall bias occurs when participants do not accurately remember past events or experiences, which can affect the validity of study findings. This type of bias is particularly relevant in studies that rely on participants’ retrospective accounts of their past behaviors, exposures, or medical history.

Cross-sectional and case-control studies are more susceptible to recall bias because they typically ask participants to recall past events after the disease or outcome of interest has occurred. In a case-control study, for instance, researchers compare individuals with the outcome (cases) to those without it (controls) and often rely on the participants' memories to gather data about prior exposures. If individuals with the outcome have differing recollections compared to those without it, the data collected can be skewed.

In contrast, randomized controlled trials, cohort studies, and longitudinal studies primarily collect data going forward over time or manipulate variables to reduce reliance on participant recall of past behavior, thus minimizing the risk of recall bias. Therefore, the correct choice highlights the vulnerability of cross-sectional and case-control studies to this specific type of bias.