Overview of Study Designs: A Deep Dive Into Research Quality Assessment

Life presents a web of interconnected causes and effects, transforming the simple art of observation into a deceptively complex affair. Study designs were created to address this complexity, though no study design is ideal. The current paper reviews the major study designs, providing tips to research-consuming clinicians for spotting lapses in validity through the introduction of confounding, selection, and information biases. This article touches on randomized control trials, post hoc analyses, randomized crossover trials, quasi-experimental trials, cohort studies, case-control studies, cross-sectional studies, case series, case reports, and expert opinion. The purpose of this review is to move the reader beyond the tidy realm of simple rules and bias forms into the nuanced mire that is research quality assessment.