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Re: st: RE: sensitivity and specificity with CI's


From   Phil Clayton <philclayton@internode.on.net>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: sensitivity and specificity with CI's
Date   Sat, 16 Jun 2012 20:03:22 +1000

Precise literature references please. See section 3.4 of the Statalist FAQ.

I guess you're talking about this article:
Watkins C, Daniels L, Jack C, Dickinson H, van Den Broek M. Accuracy of a single question in screening for depression in a cohort of patients after stroke: comparative study. BMJ. 2001 Nov 17;323(7322):1159.

I can't see how they've calculated the CIs. I would not lose sleep over it - if you look at the pre-publication history they didn't even include CIs originally, and they haven't bothered to describe their methodology. If you're desperate to find out you could contact the corresponding author.

The prevalence is just the proportion of people with the disease. In this case they state that 43 of 79 patients (54%) had depression. This is also given in the -diagt- output.

Phil

On 16/06/2012, at 11:08 AM, Fran Baker wrote:

> Thanks that's great Paul.
> 
> I am looking at a paper by Watkins et al (2001) and trying to match their calculations.
> 
> using       diagti 37 6 8 28  goes well except for the 95%CI's of sensitivity and specificity
> 
> The paper gives 95%CI's as 
> sp = 78%   (65 to 91%)
> sn = 86% (75 to 97%)
> Have you any idea how these may have been calculated - tried all cii options
> 
> Also the prevalence is given as 54%.  Do you know how this is found?
> 
> Cheers
> Fran
> 
>>>> "Visintainer, Paul" <Paul.Visintainer@baystatehealth.org> 15/06/2012 11:41 pm >>>
> You can use -diagt-, which provides CIs.  You can also compute the confidence intervals using -ci-, since sensitivity and specificity are proportions
> 
> -Paul
> 
> -----Original Message-----
> From: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] On Behalf Of Fran Baker
> Sent: Friday, June 15, 2012 9:14 AM
> To: statalist@hsphsun2.harvard.edu 
> Subject: st: sensitivity and specificity with CI's
> 
> Hi 
> 
> Is there a command for calculating sensitivity and specificity with CI's?  Have looked and found some but not sure of the quality and there don't appear to be CI's.
> 
> Thanks
> Fran
> 
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