An S-learner is a simple causal estimation method: train one machine-learning model using treatment X and confounders Z, then predict outcomes under alternative treatment values. It applies these predictions within the adjustment formula to estimate quantities such as E[Y|do(X = x)] and the average treatment effect (ATE). section 4.2.4
Estimate an intervention by following these steps:
- Train a model f on historical observations containing treatment X, outcome Y, and all confounders Z1, …, Zp. section 4.2.4
- Use a classifier for categorical outcomes or a regressor for continuous outcomes. section 4.2.4
- For every observation, replace its observed treatment with the value of interest, such as X = 1 and X = 0, while retaining its confounders. section 4.2.4
- Average the predicted outcomes to estimate the ATE; the single-model approach is simple but can produce unrealistic results depending on the data. section 4.2.4
