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st: sensitivity, specifity and missing data


From   BISSERY Alvine <Alvine.BISSERY@hop.egp.ap-hop-paris.fr>
To   "'statalist@hsphsun2.harvard.edu'" <statalist@hsphsun2.harvard.edu>
Subject   st: sensitivity, specifity and missing data
Date   Mon, 03 Feb 2003 12:39:59 +0100

Dear list, 

I want to estimate the specifity of a test. Response of the test are :
"disease", "not disease", and "i don't know"
The gold standart gives : "disease" , "not disease".

What do I have to do with the answer "I don't know" .. how can I estimate
the specificity ?


Thank you 

Alvine Bissery 

> -----Message d'origine-----
> De: Friederike Barthel [mailto:FriederikeB@ctu.mrc.ac.uk]
> Date: lundi 27 janvier 2003 16:48
> : 'statalist@hsphsun2.harvard.edu'
> Objet: st: sample size program
> 
> 
> Dear list
> 
> i have written the following program in order to calculate 
> the sample size
> (i want to advance on it which is why i didnt use sampsi) but 
> it returns an
> error message and I can't spot the error at present.
> 
> program define sampsi1
> 
> version 7.0
> 
> syntax [, ZAlpha (real 1.645) ZPower (real 0.8416) HRatio 
> (real 1.5) CEnsor
> (real 0.8) PControl (real 0.5)]
> 
> if "`ZAlpha'"==" {
> ret local errmess "zalpha required"
> exit 198
> }
> 
> if `zalpha'<=0 {
> ret local errmess "zalpha() out of range"
> exit 198
> }
> 
> if "`zpower'"==" {
> ret local errmess "zpower required"
> exit 198
> }
> 
> if `zpower'<=0 {
> ret local errmess "zpower() out of range"
> exit 198
> }
> 
> if "`hratio'"==" {
> ret local errmess "hratio required"
> exit 198
> }
> 
> if `hratio' <= 0 {
> ret local errmess "hratio out of range"
> exit 198
> }
> 
> if "`censor'"==" {
> ret local errmess "censor required"
> exit 198
> }
> 
> if `censor'<=0 | `censor'>=1 {
> ret local errmess "censor out of range"
> exit 198
> }
> 
> if "`pcontrol'"==" {
> ret local errmess "pcontrol needed"
> exit 198
> }
> 
> if `pcontrol'<=0 | `pcontrol'>=1 {
> ret local errmess "pcontrol out of range"
> exit 198
> }
> 
> tempname N0 N1 N2 N
> 
> scalar `N0' = (`ZAlpha'+`ZPower')^2
> scalar `N1'=(log(`HRatio'))^2
> scalar `N2'=`CEnsor'*`PControl'*(1-`PControl')
> scalar `N'=`N0'/(`N1'*`N2')
> 
> return N=`N'
> 
> end
> 
> exit
> 
> Thank you for your help
> 
> Sophie
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