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A Negative Correlation Strategy for Bracketing in Difference-in-Differences

Ting Ye, Luke Keele, Raiden Hasegawa, Dylan S. Small

arXiv 3 Jun 2020 · Statistics — Methodology · publishedJournal of the American Statistical Association (2023) · 15 citations (OpenAlex)

arXiv:2006.02423 · PDF · DOI · OpenAlex · Extracted main text

Abstract

The method of difference-in-differences (DID) is widely used to study the causal effect of policy interventions in observational studies. DID employs a before and after comparison of the treated and control units to remove bias due to time-invariant unmeasured confounders under the parallel trends assumption. Estimates from DID, however, will be biased if the outcomes for the treated and control units evolve differently in the absence of treatment, namely if the parallel trends assumption is violated. We propose a general identification strategy that leverages two groups of control units whose outcomes relative to the treated units exhibit a negative correlation, and achieves partial identification of the average treatment effect for the treated. The identified set is of a union bounds form that involves the minimum and maximum operators, which makes the canonical bootstrap generally inconsistent and naive methods overly conservative. By utilizing the directional inconsistency of the bootstrap distribution, we develop a novel bootstrap method to construct uniformly valid confidence intervals for the identified set and parameter of interest when the identified set is of a union bounds form, and we establish the method's theoretical properties. We develop a simple falsification test and sensitivity analysis. We apply the proposed strategy for bracketing to study whether minimum wage laws affect employment levels.

Citation extraction

58
references
101
in-text mentions
58
distinct cited
1
self-citations
10,975
main-text words

appendix boundary found by appendix_titled_section at “Supplementary Material” · 59% of the source is main text. Read the extracted text to check this.

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
1Manski, C. F. and Pepper, J. V (2018) How do right-to-carry laws affect crime rates? coping with ambiguity using bounded-variation assumptions0.84333100%
2Berger, R. L. and Hsu, J. C (1996) Bioequivalence trials, intersection-union tests and equivalence confidence sets0.84333100%
3Hasegawa, R. B., Webster, D. W., and Small, D. S (2019) Bracketing in the comparative interrupted time-series design to address concerns about history interacting with group: Evaluatin… self0.81115453%
4Chernozhukov, V., Lee, S., and Rosen, A. M (2013) Intersection bounds: estimation and inference0.81142100%
5Athey, S. and Imbens, G. W (2006) Indentification and inference in nonlinear difference-in-difference models0.7373367%
6Donald, S. G. and Lang, K (2007) Inference with differences-in-differences and other panel data0.73732100%
7Romano, J. P. and Shaikh, A. M (2012) On the uniform asymptotic validity of subsampling and the bootstrap0.6444250%
8Derenoncourt, E. and Montialoux, C (2021) Minimum wages and racial inequality0.64441100%
9Angrist, J. D. and Pischke, J.-S (2009) Mostly Harmless Econometrics0.64422100%
10Bertrand, M., Duflo, E., and Mullainathan, S (2004) How much should we trust differences-in-differences estimates?0.64422100%

Showing the top 10 of 58 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
1rdid and rdidstag: Stata commands for robust difference-in-differences1.000123
2What's Trending in Difference-in-Differences? A Synthesis of the Recent Econometrics Literature0.58531
3Synthetic Parallel Trends0.51121
4Bounds for Treatment Effects in the Presence of Anticipatory Behavior0.40511
5Robust difference-in-differences models0.40511
6A Semiparametric Instrumented Difference-in-Differences Approach to Policy Learning0.40511
7Difference-in-differences Design with Outcomes Missing Not at Random0.40511
8Potential Outcome Modeling and Estimation in DiD Designs with Staggered Treatments0.40511
9On a Debiased and Semiparametric Efficient Changes-in-Changes Estimator0.40511