Causal Inference without Balance Checking: Coarsened Exact Matching
Open accessAbstract
We discuss a method for improving causal inferences called “Coarsened Exact Matching” (CEM), and the new “Monotonic Imbalance Bounding” (MIB) class of matching methods from which CEM is derived. We summarize what is known about CEM and MIB, derive and illustrate several new desirable statistical properties of CEM, and then propose a variety of useful extensions. We show that CEM possesses a wide range of statistical properties not available in most other matching methods but is at the same time exceptionally easy to comprehend and use. We focus on the connection between theoretical properties and practical applications. We also make available easy-to-use open source software for R, Stata , and SPSS that implement all our suggestions.
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Because pruned data are used, the treatment effect cannot be claimed for whole population; estimand is local average treatment effect for treated.
“Since we are using pruned data, we cannot claim to measure the treatment effect on the whole population.Rather, the estimand in our statistical models is the local average treatment effect for the treated (Iacus et al., 2012).”
From Relative Feedback Increases Disparities in Effort and Performance in Crowdsourcing Contests (2022) · cites this paper as Iacus et al., 2012
Section 6.3.3 defines the estimand after matching as the average treatment effect for the matched people, which the paper calls a “local SATT.” But Section 2.3 says pruning only control units leaves the target quantity unchanged; the shift to a local estimand depends on pruning treated units, not merely on using pruned data. (LLM, conf=0.85)
Experimental — accuracy not yet measuredUsing CEM improves estimation by reducing covariate imbalance between treated and control groups.
“To remedy this, we use Coarsened Exact Matching (CEM) to improve the estimation by reducing the imbalance in covariates between treated and control groups (Blackwell et al. 2009, Iacus et al. 2012).”
From Skill-Biased Technical Change, Again? Online Gig Platforms and Local Employment (2025) · cites this paper as Iacus et al. 2012
The key property of CEM is that it is in a class of methods called Monotonic Imbalance Bounding, which bounds the maximum imbalance in some feature of the empirical distributions through an ex-ante choice by the user.
“The key property of CEM is that it is in a class of methods called Monotonic Imbalance Bounding, which bounds the maximum imbalance in some feature of the empirical distributions through an exante choice by the user.”
From Drivers of green bond issuance and new evidence on the 'greenium' (2021) · cites this paper as Iacus et al. 2012
CEM is considered a better alternative to PSM because CEM reduces the model dependence of the matching that is inherent in PSM.
“In our study, we employ coarsened exact matching (CEM), which is considered to be a better alternative to PSM, because CEM reduces the model dependence of the matching that is inherent in PSM (Iacus et al. 2012).”
From Drivers of green bond issuance and new evidence on the 'greenium' (2021) · cites this paper as Iacus et al. 2012
CEM reduces imbalances of covariates between treated and control groups.
“CEM reduces imbalances of covariates between treated and control groups.”
From Drivers of green bond issuance and new evidence on the 'greenium' (2021) · cites this paper as Iacus et al. 2012
The results are made more robust by estimating the DiD model using weights generated using CEM.
“We make our results more robust by estimating our DiD model using weights generated using CEM 67 .”
From The effects of remote work on collaboration among information workers (2021) · cites this paper as [67]
We used coarsened exact matching to identify matching control papers for as many retracted papers as possible.
“To ensure that we identified matching control papers for as many retracted papers as possible, we used coarsened exact matching (60).”
From Dynamics of cross-platform attention to retracted papers (2022) · cites this paper as [60]
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- Authors
- Iacus, S. M., King, G., & Porro, G.
- Affiliations
- University of Milan (IT)
- Harvard University (US)
- University of Trieste (IT)
- Corresponding author
- King, Gary
- Venue
- Political Analysis
- Publisher
- Cambridge University Press (CUP)
- Published
- 2012
- Volume
- 20
- Issue
- 1
- Pages
- 1-24
- ISSN
- 1047-1987 (ISSN-L)
- 1476-4989
- OpenAlex
- W2029941278
- Semantic Scholar
- 69bc307169754c186f224dcaabf38f7959afe9a1
- Cited by
- 3,563
- References
- 55
- Citations by year
- 2026: 283 · 2025: 364 · 2024: 360 · 2023: 360 · 2022: 350 · 2021: 395 · 2020: 330 · 2019: 249 · 2018: 219 · 2017: 141 · 2016: 155 · 2015: 102 · 2014: 109 · 2013: 69 · 2012: 42
- FWCI
- 67.11
- Type
- journal article
- Language
- en
- Open access
- bronze
- doi.org
- Locations
- Political Analysis (publishedVersion)
- RePEc: Research Papers in Economics (submittedVersion)
- Archivio Istituzionale della Ricerca (Universita Degli Studi Di Milano) (submittedVersion, other-oa)
- IrInSubria (University of Insubria) (submittedVersion)
- Topics
- Physical Sciences › Mathematics › Statistics and Probability › Advanced Causal Inference Techniques
- Social Sciences › Sociology and Political Science › Qualitative Comparative Analysis Research
- Physical Sciences › Mathematics › Statistics and Probability › Statistical Methods and Bayesian Inference
- Keywords
- coarsened exact matching, causal inference, matching methods, treatment effect estimation
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