ARCHE Blog

A cross-sectional study examines a population at one specific point in time – like taking a “snapshot” of a group’s health status. These studies measure both exposures and outcomes simultaneously, making them ideal for estimating prevalence but not for proving causation.

A cohort study follows a group of people over time to see how exposures affect outcomes. There are prospective and retrospective types, powerful for establishing temporal sequences but potentially expensive.

A case-control study identifies people with an outcome (cases) and compares them to those without (controls), looking backward at exposures. Efficient for rare diseases but requires careful control selection.

An RCT randomly assigns participants to intervention or control groups, considered the gold standard for testing causal effects due to randomization balancing confounders.