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S-learner

As explained in Causal Inference for Data Science

An S-learner is a causal estimation algorithm that fits one outcome model containing the treatment and confounders and predicts outcomes under alternative treatment values.

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

How Causal Inference for Data Science covers it

How deep it goes
Defines a four-step prediction procedure and notes unrealistic results as a data-dependent limitation.
Examples
Uses historical treatment-outcome-confounder rows, binary treatment values 1 and 0, classifiers, and regressors.
What it assumes
Assumes adjustment-formula reasoning, historical observations, treatment values, outcomes, and measured confounders.
What you can do after
Apply one trained model to estimate intervention-specific outcomes and the average treatment effect.
How it connects
Connects machine learning with the adjustment formula, ATE, T-learner, and cross-fitting.

Related concepts

This explainer was generated by Manning's knowledge graph from the text of Causal Inference for Data Science. The section links point to the parts of the book it draws on.