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A Semiparametric Instrumented Difference-in-Differences Approach to Policy Learning

Pan Zhao, Yifan Cui

arXiv 14 Oct 2023 · Statistics — Methodology · publishedBiometrika (2025) · 1 citations (OpenAlex)

arXiv:2310.09545 · PDF · DOI · OpenAlex · Extracted main text

Abstract

Recently, there has been a surge in methodological development for the difference-in-differences (DiD) approach to evaluate causal effects. Standard methods in the literature rely on the parallel trends assumption to identify the average treatment effect on the treated. However, the parallel trends assumption may be violated in the presence of unmeasured confounding, and the average treatment effect on the treated may not be useful in learning a treatment assignment policy for the entire population. In this article, we propose a general instrumented DiD approach for learning the optimal treatment policy. Specifically, we establish identification results using a binary instrumental variable (IV) when the parallel trends assumption fails to hold. Additionally, we construct a Wald estimator, novel inverse probability weighting (IPW) estimators, and a class of semiparametric efficient and multiply robust estimators, with theoretical guarantees on consistency and asymptotic normality, even when relying on flexible machine learning algorithms for nuisance parameters estimation. Furthermore, we extend the instrumented DiD to the panel data setting. We evaluate our methods in extensive simulations and a real data application.

Citation extraction

76
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107
in-text mentions
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distinct cited
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Most heavily cited references

The works this paper leans on most, across its whole bibliography — not restricted to papers in our corpus. Ranked by composite intensity, which combines how often a work is mentioned, how many sections mention it, and how much of that falls in the main text rather than the appendix.

ReferenceIntensityMentionsSectionsMain text
1Yifan Cui and Eric Tchetgen Tchetgen (2021) A semiparametric instrumental variable approach to optimal treatment regimes under endogeneity self0.92843100%
2Ting Ye, Ashkan Ertefaie, James Flory, Sean Hennessy, and Dylan S Sm… (2022) Instrumented difference-in-differences0.8947671%
3Alberto Abadie (2005) Semiparametric difference-in-differences estimators0.84333100%
4Susan Athey and Stefan Wager (2021) Policy learning with observational data0.73732100%
5Liangjun Su, Irina Murtazashvili, and Aman Ullah (2013) Local linear gmm estimation of functional coefficient iv models with an application to estimating the rate of return to schooling0.6444250%
6Yichun Hu, Nathan Kallus, and Xiaojie Mao (2022) Fast rates for contextual linear optimization0.64422100%
7Alexander R Luedtke and Mark J van der Laan (2016) Statistical inference for the mean outcome under a possibly non-unique optimal treatment strategy0.64422100%
8Alexander Luedtke and Antoine Chambaz (2020) Performance guarantees for policy learning0.64422100%
9Zhengling Qi, Rui Miao, and Xiaoke Zhang (2023) Proximal learning for individualized treatment regimes under unmeasured confounding0.64422100%
10Tat-Thang Vo, Ting Ye, Ashkan Ertefaie, Samrat Roy, James Flory, Sea… (2022) Structural mean models for instrumented difference-in-differences0.64422100%

Showing the top 10 of 76 scored citations.

Cited by, within the corpus

arXiv econ.EM papers that cite this one, ranked by how heavily they lean on it.

Citing paperIntensityMentionsSections
1On a Debiased and Semiparametric Efficient Changes-in-Changes Estimator0.40511
2Policy Learning with $$-Expected Welfare0.00011