Worked Derivations for Classical Epidemiological Measures // Computes classical epidemiological measures and returns the complete worked derivation alongside the result: every intermediate quantity, the formula, and the formula with the observed numbers substituted in. Intended for teaching, for checking hand calculations, and for generating worked solutions in course materials. Scope is deliberately limited to methods a student can compute by hand on paper. Methods follow Mantel and Haenszel (1959) doi:10.1093/jnci/22.4.719, Greenland and Robins (1985, Biometrics 41, 55-68), Robins, Breslow and Greenland (1986, Biometrics 42, 311-323), and Breslow and Day (1980, IARC Scientific Publications No. 32).