A study that looks back at existing data to examine past exposures and outcomes.
A retrospective study analyzes data or records collected before the study was designed, looking backward from an outcome (e.g., an injury) to identify prior exposures or risk factors. It is generally quicker and cheaper than prospective research but is more vulnerable to recall bias, selection bias, and incomplete or inconsistent historical records, so causal inference should be made cautiously. The term covers a range of designs (e.g., case-control, retrospective cohort), and rigor varies considerably between them.
This guide was auto-drafted and is pending editorial review.