MEAN COST RATING (MCR) IS SOMERS' D: A METHODOLOGICAL

• NCJ Number: 147958
• Journal: Journal of Criminal Justice Volume: 22 Issue: 1 Dated: (1994) Pages: 63-70
• Author(s): M A Greene; P B Hoffman; J L Beck
• Date Published: 1994
• Length: 8 pages
• Publication Format: Article
• Publication Type: Report (Technical Assistance)
• Language: English
• Country: United States of America
• Note: *This document is currently unavailable from NCJRS.

Annotation

This paper's purpose is to demonstrate that the Mean Cost Rating (MCR), a particularly useful statistic for measuring the accuracy of instruments used to predict recidivism, actually is a special case of the statistic called Somers' D.

Abstract

Somers' D, normally used to measure concordance in a contingency table, is reported on the output of commonly used statistical packages. Consequently, researchers who wish to use the MCR can obtain this statistic without any special programming or time-consuming hand calculations. However, some caution must be used in obtaining the MCR from a statistical package, because Somers' D has two forms. In one form, the rows are the independent variable; in the other, the columns are the independent variable. The MCR is the form of Somers' D that is opposite to what might be expected. (Author abstract modified)