Prediction-powered Generalization of Causal Inferences

Ilker Demirel, Ahmed Alaa, Anthony Philippakis, David Sontag

Abstract: Causal inferences from a randomized controlled trial (RCT) may not pertain to a *target* population where some effect modifiers have a different distribution. Prior work studies *generalizing* the results of a trial to a target population with no outcome but covariate data available. We show how the limited size of trials makes generalization a statistically infeasible task, as it requires estimating complex nuisance functions. We develop generalization algorithms that supplement the trial data with a prediction model learned from an additional *observational* study (OS), without making *any* assumptions on the OS. We theoretically and empirically show that our methods facilitate better generalization when the OS is "high-quality", and remain robust when it is not, and *e.g.*, have unmeasured confounding.

Submission Number: 7239