Optimal weighting for estimating generalized average treatment effects

In causal inference, a variety of causal effect estimands have been studied, including the sample, uncensored, target, conditional, optimal subpopulation, and optimal weighted average treatment effects. Ad hoc methods have been developed for each estimand based on inverse probability weighting (IPW)...

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Main Authors: Kallus Nathan, Santacatterina Michele
Format: Article
Language:English
Published: De Gruyter 2022-05-01
Series:Journal of Causal Inference
Subjects:
Online Access:https://doi.org/10.1515/jci-2021-0018
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author Kallus Nathan
Santacatterina Michele
author_facet Kallus Nathan
Santacatterina Michele
author_sort Kallus Nathan
collection DOAJ
description In causal inference, a variety of causal effect estimands have been studied, including the sample, uncensored, target, conditional, optimal subpopulation, and optimal weighted average treatment effects. Ad hoc methods have been developed for each estimand based on inverse probability weighting (IPW) and on outcome regression modeling, but these may be sensitive to model misspecification, practical violations of positivity, or both. The contribution of this article is twofold. First, we formulate the generalized average treatment effect (GATE) to unify these causal estimands as well as their IPW estimates. Second, we develop a method based on Kernel optimal matching (KOM) to optimally estimate GATE and to find the GATE most easily estimable by KOM, which we term the Kernel optimal weighted average treatment effect. KOM provides uniform control on the conditional mean squared error of a weighted estimator over a class of models while simultaneously controlling for precision. We study its theoretical properties and evaluate its comparative performance in a simulation study. We illustrate the use of KOM for GATE estimation in two case studies: comparing spine surgical interventions and studying the effect of peer support on people living with HIV.
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spelling doaj.art-899d97d9d0df482abd9d770f2809d8042022-12-22T02:01:42ZengDe GruyterJournal of Causal Inference2193-36852022-05-0110112314010.1515/jci-2021-0018Optimal weighting for estimating generalized average treatment effectsKallus Nathan0Santacatterina Michele1School of Operations Research and Information Engineering and Cornell Tech, Cornell University, New York 10044, New York, USADepartment of Population Health, New York University Grossman School of Medicine, New York 10016, New York, USAIn causal inference, a variety of causal effect estimands have been studied, including the sample, uncensored, target, conditional, optimal subpopulation, and optimal weighted average treatment effects. Ad hoc methods have been developed for each estimand based on inverse probability weighting (IPW) and on outcome regression modeling, but these may be sensitive to model misspecification, practical violations of positivity, or both. The contribution of this article is twofold. First, we formulate the generalized average treatment effect (GATE) to unify these causal estimands as well as their IPW estimates. Second, we develop a method based on Kernel optimal matching (KOM) to optimally estimate GATE and to find the GATE most easily estimable by KOM, which we term the Kernel optimal weighted average treatment effect. KOM provides uniform control on the conditional mean squared error of a weighted estimator over a class of models while simultaneously controlling for precision. We study its theoretical properties and evaluate its comparative performance in a simulation study. We illustrate the use of KOM for GATE estimation in two case studies: comparing spine surgical interventions and studying the effect of peer support on people living with HIV.https://doi.org/10.1515/jci-2021-0018average treatment effectcausal inferencecovariate balancemisspecificationoptimizationpositivity92b1592c6062n9962p10
spellingShingle Kallus Nathan
Santacatterina Michele
Optimal weighting for estimating generalized average treatment effects
Journal of Causal Inference
average treatment effect
causal inference
covariate balance
misspecification
optimization
positivity
92b15
92c60
62n99
62p10
title Optimal weighting for estimating generalized average treatment effects
title_full Optimal weighting for estimating generalized average treatment effects
title_fullStr Optimal weighting for estimating generalized average treatment effects
title_full_unstemmed Optimal weighting for estimating generalized average treatment effects
title_short Optimal weighting for estimating generalized average treatment effects
title_sort optimal weighting for estimating generalized average treatment effects
topic average treatment effect
causal inference
covariate balance
misspecification
optimization
positivity
92b15
92c60
62n99
62p10
url https://doi.org/10.1515/jci-2021-0018
work_keys_str_mv AT kallusnathan optimalweightingforestimatinggeneralizedaveragetreatmenteffects
AT santacatterinamichele optimalweightingforestimatinggeneralizedaveragetreatmenteffects