What to call your medical records-based study

In veterinary clinical research, the terms "retrospective study" and "prospective study," when not accompanied by a description of the observational study design, are prone to misinterpretation. Cohort, case-control, cross-sectional, and case series may all be retrospective or prospective depending on the sampling timing. In this Viewpoint article, we present a simple tool and use published clinical examples to help investigators accurately identify and report their study designs. As the timing of data collection and the study design impact the risk of bias, we remind authors that "retrospective" (or its antonym, "prospective") should always be accompanied by a study design term.