Which of the following best describes a retrospective study?

A retrospective study is characterized by its focus on examining past exposures or factors and how they relate to an established outcome. This type of study typically involves looking back at historical data to evaluate how prior events, behaviors, or conditions may have influenced the occurrence of a certain disease or health outcome in a population. Researchers may analyze patient records, interviews, or other data sources that provide information from the past to identify correlations and potential causative factors.

In contrast, data collected in real-time relates more to prospective studies, which gather information as events unfold. Looking forward to predict outcomes also aligns with prospective studies or longitudinal studies, where researchers follow a group over time to see how certain variables impact future results. Evaluating outcomes as they occur describes a real-time or concurrent approach to data collection, again more typical of prospective studies. Therefore, the defining feature of a retrospective study is its retrospective examination of past exposures in relation to health outcomes.