Which type of study involves comparing two different groups based on their outcomes?

A case-control study is focused on comparing two different groups based on a specific outcome. In this type of study, researchers start by identifying individuals who have a particular outcome (cases) and those who do not (controls). The goal is to look back retrospectively to determine if there are differences in exposure to potential risk factors between the two groups. This retrospective design allows researchers to infer associations between risk factors and outcomes.

For example, if a researcher is investigating the relationship between smoking and lung cancer, they would compare a group of lung cancer patients (cases) to a group of individuals without lung cancer (controls), assessing their past smoking habits to determine whether smoking is more common in the cases than in the controls.

This distinguishes case-control studies from other types. Experimental studies manipulate an independent variable to observe its effect on a dependent variable, while longitudinal studies track the same individuals over time to observe changes or developments in outcomes. Cross-sectional studies provide a snapshot of a population at one point in time, examining the prevalence of an outcome or characteristic but not the causal relationships between variables.