Regression discontinuity design in criminal justice evaluation: an introduction and illustration.

BACKGROUND

Corrections agencies frequently place offenders into risk categories, within which offenders receive different levels of supervision and programming. This supervision strategy is seldom evaluated but often can be through routine use of a regression discontinuity design (RDD). This article argues that RDD provides a rigorous and cost-effective method for correctional agencies to evaluate and improve supervision strategies and advocates for using RDD routinely in corrections administration. The objective is to better employ correctional resources.

METHOD

This article uses a Neyman-Pearson counterfactual framework to introduce readers to RDD, to provide intuition for why RDD should be used broadly, and to motivate a deeper reading into the methodology. The article also illustrates an application of RDD to evaluate an intensive supervision program for probationers.

RESULT

Application of the RDD, which requires basic knowledge of regressions and some special diagnostic tools, is within the competencies of many criminal justice evaluators. RDD is shown to be an effective strategy to identify the treatment effect in a community corrections agency using supervision that meets the necessary conditions for RDD.

CONCLUSION

The article concludes with a critical review of how RDD compares to experimental methods to answer policy questions. The article recommends using RDD to evaluate whether differing levels of control and correction reduce criminal recidivism. It also advocates for routine use of RDD as an administrative tool to determine cut points used to assign offenders into different risk categories based on the offenders' risk scores.