When estimating whether a treatment changes an outcome, augmented inverse probability weighting (AIPW) combines an outcome model with inverse-probability treatment weighting. Its doubly robust design remains unbiased when either component is correctly specified. section 8.3
AIPW brings together two estimates built from the same confounder information:
- A T-learner estimates the expected outcome under treatment and control, using functions that approximate E[Y|C,T=1] and E[Y|C,T=0]. section 8.3
- IPW estimates each subject’s treatment probability, or propensity score, and uses those probabilities for weighting. section 8.3
- The AIPW estimator augments the weighting estimate with outcome-model predictions, providing protection if one model is unbiased. section 8.3
The setup assumes a binary treatment, an observed outcome, measured confounders, and no unobserved confounders. AIPW is recommended for binary-treatment problems because it is root-n consistent, efficient, and supports uncertainty estimates through confidence intervals. section 8.3 section 8.6
Table 8.4 Available data with propensity scores calculated
|
Y
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T
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C
1
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…
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Cp
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|---|---|---|---|---|
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y
1
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t
1
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c
1
1
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…
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c
1
p
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…
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…
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…
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…
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…
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y
n
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t
n
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c
n
1
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…
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c
n
p
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Use the treatment, outcome, and confounder columns as the data structure required before calculating propensity scores and applying AIPW. section 8.3
Estimating treatment effects with DoubleML
In the right-heart catheterization dataset, estimate the average treatment effect of swang1 on death and calculate its confidence interval with DoubleML. The package exposes AIPW through its interactive regression model (IRM), with hyperparameter tuning performed on cross-fitting folds. section 8.3.1
