on 19/12/2003 08:32, fmedeiros at [email protected] wrote:
> Is there a minimum number of categories to adequately fit a
> parametric ROC curve for ordinal data? For example, can we
> adequately fit a model when we have only 3 categories (for
> instance, abnormal, borderline and normal)
You could try -nproc- by Philip Price and Fred Wolfe. But with so few
categories, you would be better off looking at the performance of individual
cutoff points on the scale in terms of sensitivity, specificity, positive
and negative predictive values. The ROC area is a very broad brush, and does
not assess the suitability of a test for specific purposes.
Ronan M Conroy ([email protected])
Lecturer in Biostatistics
Royal College of Surgeons
Dublin 2, Ireland
+353 1 402 2431 (fax 2764)
--------------------
There is no planet B
--------------------------------------------------------------------------------------------------------------------
This email and any files transmitted with it are confidential and
intended solely for the use of the individual or entity to whom
they are addressed.
If you have received this email in error please notify the
originator of the message. This footer also confirms that this
email message has been scanned for the presence of computer viruses.
Any views expressed in this message are those of the individual
sender, except where the sender specifies and with authority,
states them to be the views of The Royal College Of Surgeons in Ireland.
--------------------------------------------------------------------------------------------------------------------
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
