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Re: st: comparison of diagnostic procedures


From   Gary Longton <glongton@fhcrc.org>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: comparison of diagnostic procedures
Date   Thu, 08 Sep 2005 10:31:00 -0700

htzvara (?) wrote:

>>> i have one variable which represents if the patient has the disease
>>> (coding:
>>> 0-
>>> 1)--and this is standard.
>>> Additionally i have 12 more variables which represents the outcome of 12
>>> different diagnostic procedures (coding: 0-1 for all of them).I want
>>> to find
>>> which is the best diagnostic procedure. I calculate the sensitivity and
>>> specificity and their confidence intervals for each of them. If the
>>> confidence
>>> interval for the sensitivity of one diagnostic procedure do not
>>> overlap the
>>> confidence interval for the Se of another diagnostic procedure then the
>>> difference is significant.
>>> Is there any test to perform and give p_value? Is there a need to make a
>>> correction for multiple comparisons.?

and Michael P. Mueller replied:

You might want to take a look at this book: Pepe, M.S. (2003). Statistical Evaluation of Medical Tests for Classification and Prediction. Dr. Pepe has Stata programs on her webpage you can download.
Hope this helps,
To follow-up on Michael's suggestions with a link and a pointer to specific programs that might be useful -

The webpage for Margaret's book can be found at:

http://www.fhcrc.org/science/labs/pepe/book/

The specific programs that might be helpful for evaluating binary screening tests are -binscrn1-, -binscrn2-, and -binscrn3-. The first of these provides estimates and CI's (Wilson, Clopper-Pearson, and logit-based) for true and false positive fractions (i.e. sensitivity and 1-specificity), positive and negative predictive values (assuming cohort data), and Diagnostic likelihood ratios. The 2nd and 3rd programs compare these measures for 2 screening tests, given unpaired and paired data, respectively.

Have been meaning to submit these as a package to SSC.

- Gary


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