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Updated: Jun 4, 2026

Inverse Probability of Treatment Weighting (Propensity Score) using the Military Health System Data Repository and National Death Index
Published on: January 8, 2020
The role of the c-statistic in variable selection for propensity score models
Daniel Westreich1, Stephen R Cole, Michele Jonsson Funk
1Department of Obstetrics and Gynecology and Duke Global Health Institute, Duke University, Durham, NC, USA. daniel.westreich@duke.edu
The c-statistic is often misused to assess propensity scores for confounding control. Relying on it can harm study precision and generalizability, making it an unreliable metric for observational research.
Area of Science:
- Epidemiology
- Biostatistics
- Observational Research Methods
Background:
- Propensity scores are used to control confounding in observational studies.
- The c-statistic is frequently cited as a measure of propensity score performance.
Purpose of the Study:
- To evaluate the utility of the c-statistic in assessing propensity score models.
- To highlight the limitations of using the c-statistic for confounding control.
Main Methods:
- Review of applied literature on propensity score methodology.
- Conceptual analysis of the c-statistic's role in propensity score construction.
Main Results:
- A high c-statistic does not guarantee effective confounding control.
- Using the c-statistic may reduce overlap between treated and untreated groups.
- This reduction can necessitate population restrictions, impacting precision and generalizability.
Conclusions:
- The c-statistic is an inadequate metric for evaluating propensity scores.
- Variable selection should prioritize subject matter knowledge, empirical data, and sensitivity analyses for robust confounding control.
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