Thanks.
I re-read the footnote on my SPSS output, and as it turns out, "a. The smallest cutoff value is the minimum observed test value minus 1, and the largest cutoff value is the maximum observed test value plus 1. All the other cutoff values are the averages of two consecutive ordered observed test values."
The "test value minus 1" explains the negative value. This is a valuable lesson to me!
Danielle
________________________________
From: Anders Alexandersson <andersalex@gmail.com>
To: statalist@hsphsun2.harvard.edu
Sent: Thursday, July 28, 2011 4:17 PM
Subject: Re: st: ROC question: STATA vs SPSS
Please provide the syntax and outputs in SPSS and Stata if you need
help with interpreting any output differences.
Anders Alexandersson
andersalex@gmail.com
On Thu, Jul 28, 2011 at 3:53 PM, Danielle Boyce <dmboyce1@yahoo.com> wrote:
> Hi,
>
> I usually use STATA for my data analysis, but for various reasons, ran one in SPSS first. It gave me a negative cutoff point when my data have no negative values. I re-ran in STATA and got the same
AUC, but no negative cutoff, and everything else (CIs, cutoffs) are ever-so-slightly off compared to SPSS.
>
> I'm just wondering if anyone knows why this discrepancy exists.
>
> Thanks!
> Danielle
>
> *
> * For searches and help try:
> * http://www.stata.com/help.cgi?search
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
