Re: st: comparison of diagnostic procedures

["Michael P. Mueller" <michael.mueller@utoronto.ca>]

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,
Michael

htzavara@med.uoa.gr wrote:


> &Agr;&rgr;&khgr;&igr;&kgr;&oacgr; &mgr;&eeacgr;&ngr;&ugr;&mgr;&agr; &agr;&pgr;&oacgr;  Svend Juul <SJ@SOCI.AU.DK>:
>
>  
>
> > 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.?
> >
> > ----
> >
> > It is not quite clear to me what you want. If it is to find the single test
> > that has the "best" predictive value, try Paul Seed's -diagt-  (findit
> > diagt). However, you must look at both sensitivity and specificity to get a
> > meaningful assessment.
> >
> > I am not sure why you want to test whether the sensitivity of two tests are
> > significantly different. And the confidence interval comparison you describe
> > is quite insensititive.
> >
> > Would this show what you need:
> > Make a logistic regression followed by -lroc- (ROC analysis):
> >   . logistic disease test1-test12
> >   . lroc
> >
> > You might then try to remove tests to see whether removal makes a difference
> > to the AUC (area under curve).
> >
> > Hope this helps
> > Svend
> >
> > ________________________________________________________
> >
> > Svend Juul
> > Institut for Folkesundhed, Afdeling for Epidemiologi
> > (Institute of Public Health, Department of Epidemiology)
> > Vennelyst Boulevard 6
> > DK-8000 Aarhus C,  Denmark
> > Phone, work:  +45 8942 6090
> > Phone, home:  +45 8693 7796
> > Fax:          +45 8613 1580
> > E-mail:       sj@soci.au.dk
> > _________________________________________________________
> >
> > Thank you very much for your help.
> >    
> I know about diagt and i used it to obtain the sensitivity - specificity.
> Roc analysis cannot help as the variables which represents the diagnostic 
> tests are not continuous but dichotomous (0-1).Even if i can see, which test 
> has the best se-sp i want to perform a test to prove it.
>
> thank you again.
>  
>
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> >
> >    
>
>  
*
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