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Re: RE: st:Confidence interval of difference between two proportionsand -csi-


From   Joseph Coveney <jcoveney@bigplanet.com>
To   Statalist <statalist@hsphsun2.harvard.edu>
Subject   Re: RE: st:Confidence interval of difference between two proportionsand -csi-
Date   Fri, 19 Mar 2004 21:17:15 +0900

I've written an ado that provides Newcombe's and a few others' methods for risk 
difference (difference between proportions).  It's been lying dormant since the 
last year's NESUG, waiting for the help file to be written.  I'll see if I can 
resurrect the project to finish it off and get it to Kit Baum over the weekend, 
along with, perhaps, a similarly nearly completed command for all of Shrout & 
Fleiss's intraclass correlation coefficients, and an updated Jonckheere-
Terpstra command.

Joseph Coveney


Nick Cox wrote:

>I don't think there is any question of revising 
>the formula. Rather, I suspect that there is an 
>excellent case for adding options to -cs- to give more 
>flexibility to the user. 
>
>I see the case as very similar to that of 
>-ci, binomial-. There's been a long history 
>of different methods here and even an increasingly 
>widespread realisation that the so-called exact method
>(i.e. the Clopper-Pearson method) is often not 
>as satisfactory as other methods. (In one case, the 
>Wilson score method, that predates Clopper-Pearson.) On 
>15 July 2003 -ci- and -cii- were extended to include 
>new options -wilson-, -agresti-, and -jeffreys- for computing
>different types of binomial confidence intervals.   
>
>I suggest that -cs- needs a similar work-over. 
>       
>Nick 
>n.j.cox@durham.ac.uk 
>
>Garry Anderson
>> 
>> Thank you Roger for your suggestion of using -exactcci-
>> However, this does not calculate a risk difference and the 95% CI.
>> 
>> I suppose I am suggesting to the folks at Stata that a 
>> revised formula be 
>> used in -csi- to calculate the 95% CI of the risk difference 
>> when there is 
>> a small number of observations, and one or both have a 100% 
>> risk. Currently 
>> it is possible for the upper bound to go beyond the 
>> theoretical maximum of 
>> 100% difference.
>> 
>> I would appreciate opinions on this by others on the list.
>> 
>> Newcombe RG (1998) Interval estimation for the difference between 
>> independent proportions: comparison of eleven methods. Statistics in 
>> Medicine 17: 873-890
>> 



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