Assess students' ability to distinguish correlation from causation in observational research by testing core causal inference concepts and limitations: counterfactual reasoning, temporality, confounding, exchangeability/consistency/positivity assumptions, DAGs, common biases (confounding, selection bias, measurement error, reverse causation), basic analytic approaches (adjustment, stratification, propensity scores, instrumental variables), and sensitivity analyses. Students should be able to interpret association versus causal claims, identify potential sources of bias in study designs, state required assumptions for causal interpretation, and describe how limitations affect conclusions.