In which type of observational study do researchers compare participants with a condition to those without?

A case-control study is characterized by its focus on comparing individuals who have a specific condition or outcome (cases) with those who do not have the condition (controls). This type of study is particularly useful for investigating the causes of diseases, as it allows researchers to look back retrospectively to identify factors that may have contributed to the condition.

In this study design, the key lies in selecting participants based on their outcome status; thus, the comparison is made after the outcome has occurred. This retrospective nature enables researchers to assess potential risk factors or exposures that may have differentiated the cases from the controls. Consequently, case-control studies are efficient for studying rare conditions or diseases, as they can accumulate a sufficient number of cases more easily compared to other study designs.

In contrast, a cohort study involves following a group of individuals over time to see who develops the condition, establishing a forward-looking comparison based on exposure status. A cross-sectional study evaluates a population at a single point in time but does not involve comparison of individuals based on the outcome. An experimental study, on the other hand, involves manipulating an intervention to observe its effects, which is not applicable in this context where comparisons of existing conditions are made.