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Synthetic Controls with Staggered Adoption

Eli Ben-Michael, Avi Feller, Jesse Rothstein

arXiv 6 Dec 2019 · Statistics — Methodology · publishedJournal of the Royal Statistical Society Series B (Statistical Methodology) (2021) · 23 citations (OpenAlex)

arXiv:1912.03290 · PDF · DOI · OpenAlex · Extracted main text

Abstract

Staggered adoption of policies by different units at different times creates promising opportunities for observational causal inference. Estimation remains challenging, however, and common regression methods can give misleading results. A promising alternative is the synthetic control method (SCM), which finds a weighted average of control units that closely balances the treated unit's pre-treatment outcomes. In this paper, we generalize SCM, originally designed to study a single treated unit, to the staggered adoption setting. We first bound the error for the average effect and show that it depends on both the imbalance for each treated unit separately and the imbalance for the average of the treated units. We then propose "partially pooled" SCM weights to minimize a weighted combination of these measures; approaches that focus only on balancing one of the two components can lead to bias. We extend this approach to incorporate unit-level intercept shifts and auxiliary covariates. We assess the performance of the proposed method via extensive simulations and apply our results to the question of whether teacher collective bargaining leads to higher school spending, finding minimal impacts. We implement the proposed method in the augsynth R package.

Citation extraction

45
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112
in-text mentions
45
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
1Paglayan, A. S (2019) Public-sector unions and the size of government1.00094100%
2Abadie, A., A. Diamond, and J. Hainmueller (2015) Comparative Politics and the Synthetic Control Method1.00063100%
3Abadie, A. and J. L'Hour (2018) A penalized synthetic control estimator for disaggregated data1.00055100%
4Abadie, A., A. Diamond, and J. Hainmueller (2010) Synthetic Control Methods for Comparative Case Studies: Estimating the Effect of California's Tobacco Control Program0.9619589%
5Ben-Michael, E., A. Feller, and J. Rothstein (2019) The Augmented Synthetic Control Method self0.9507486%
6Callaway, B. and P. H. C. Sant'Anna (2020) Difference-in-Differences With Multiple Time Periods0.9285480%
7Arkhangelsky, D., S. Athey, D. A. Hirshberg, G. W. Imbens, and S. Wa… (2019) Synthetic Difference In Differences0.92843100%
8Doudchenko, N. and G. W. Imbens (2017) Difference-In-Differences and Synthetic Control Methods: A Synthesis0.92843100%
9Hoxby, C. M (1996) How teachers' unions affect education production0.87452100%
10Abadie, A (2019) Using synthetic controls: Feasibility, data requirements, and methodological aspects0.84333100%

Showing the top 10 of 45 scored citations.

Cited by, within the corpus

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Citing paperIntensityMentionsSections
1The inclusive Synthetic Control Method0.73732
2State-Building through Public Land Disposal? An Application of Matrix Completion for Counterfactual Prediction0.64422
3Large-Sample Properties of the Synthetic Control Method under Selection on Unobservables0.64422
4Synthetic Parallel Trends0.64422
5Inference for Synthetic Controls via Refined Placebo Tests0.60662
6Confidence Intervals of Treatment Effects in Panel Data Models with Interactive Fixed Effects0.51121
7Sequential Synthetic Difference in Differences0.51121
8Difference-in-Differences Meets Synthetic Control: Doubly Robust Identification and Estimation0.51121
9Causal Inference in Financial Event Studies0.51121
10Debiasing and $t$-tests for synthetic control inference on average causal effects0.40511