Past exam of the mathematics course of the University of Cambridge / 2020 / ii / Paper 2 / 5J / b

Two packs contain $40$ cigarettes. Holding height fixed, increasing average consumption from zero to two packs per day changes the log odds byThe corresponding odds ratio is thereforeThus the model estimates that a two-pack-per-day smoker has about $2.52$ times the odds of heart disease of an otherwise comparable nonsmoker. This is an association in the fitted observational model, rather than by itself a causal conclusion.