**Date:** Wed, 28 Sep 2005 08:03:30 -0700
**Reply-To:** Ian Kudel <ikudel@yahoo.com>
**Sender:** "SPSSX(r) Discussion" <SPSSX-L@LISTSERV.UGA.EDU>
**From:** Ian Kudel <ikudel@yahoo.com>
**Subject:** c statistic in logistic regression
**Content-Type:** text/plain; charset=iso-8859-1
Hi,
I am interested in calculating the c statistic for a logistic regression model. For those who do not know what it is, here is a brief description

The c statistic is a measure of the discriminative power of the logistic equation. It varies from .5 (the model's predictions are no better than chance) to 1.0 (the model always assigns higher probabilities to correct cases than to incorrect cases). Thus c is the percent of all possible pairs of cases in which the model assigns a higher probability to a correct case than to an incorrect case.

According to what I have read the c statistic is not part of SPSS output but may be calculated using the COMPUTE facility. I however have not been able to find suitable syntax or make sense of the manual provided in SPSS 13.0

Any thoughts?

Thank you.

Ian Kudel

Ian Kudel, Ph.D.
Research Scientist
Health Services Research and Development
Cincinnati VA Medical Center
3200 Vine Street
Cincinnati, Ohio
45220

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