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A Relaxation Approach to Synthetic Control

Chengwang Liao, Zhentao Shi, Yapeng Zheng

arXiv 3 Aug 2025 · Econometrics

arXiv:2508.01793 · PDF · DOI · OpenAlex · Extracted main text

Abstract

The synthetic control method (SCM) is widely used for constructing the counterfactual of a treated unit based on data from control units in a donor pool. Allowing the donor pool contains more control units than time periods, we propose a novel machine learning algorithm, named SCM-relaxation, for counterfactual prediction. Our relaxation approach minimizes an information-theoretic measure of the weights subject to a set of relaxed linear inequality constraints in addition to the simplex constraint. When the donor pool exhibits a group structure, SCM-relaxation approximates the equal weights within each group to diversify the prediction risk. Asymptotically, the proposed estimator achieves oracle performance in terms of out-of-sample prediction accuracy. We demonstrate our method by Monte Carlo simulations and by an empirical application that assesses the economic impact of Brexit on the United Kingdom's real GDP.

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60
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95
in-text mentions
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distinct cited
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11,820
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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
1Shi, Z., L. Su, and T. Xie (2025) $_2$-Relaxation: With Applications to Forecast Combination and Portfolio Analysis self1.00053100%
2Abadie, A (2021) Using Synthetic Controls: Feasibility, Data Requirements, and Methodological Aspects0.92843100%
3Ferman, B (2021) On the Properties of the Synthetic Control Estimator with Many Periods and Many Controls0.92843100%
4Ferman, B. and C. Pinto (2021) Synthetic Controls with Imperfect Pretreatment Fit0.84333100%
5Abadie, A., A. Diamond, and J. Hainmueller (2010) Synthetic Control Methods for Comparative Case Studies: Estimating the Effect of California's Tobacco Control Program0.81142100%
6Hainmueller, J (2012) Entropy Balancing for Causal Effects: A Multivariate Reweighting Method to Produce Balanced Samples in Observational Studies0.81142100%
7Bühlmann, P. and S. van de Geer (2011) Statistics for High-Dimensional Data: Methods, Theory and Applications0.73732100%
8Wainwright, M. J (2019) High-Dimensional Statistics: A Non-Asymptotic Viewpoint0.73732100%
9Zheng, X. and S. X. Chen (2024) Dynamic Synthetic Control Method for Evaluating Treatment Effects in Auto-Regressive Processes0.73732100%
10Abadie, A. and J. Gardeazabal (2003) The Economic Costs of Conflict: A Case Study of the Basque Country0.64422100%

Showing the top 10 of 60 scored citations.