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Re: st: Bootstrapping question


From   "Seed, Paul" <paul.seed@kcl.ac.uk>
To   "statalist@hsphsun2.harvard.edu" <statalist@hsphsun2.harvard.edu>
Subject   Re: st: Bootstrapping question
Date   Fri, 8 Feb 2013 12:23:24 +0000

If Henry Ilan wants a finite population correction 
to the CI for his proportion (we are told 
the population is only 140) , he can use the 
-svy- commands.  The CI for this particular population 
size is very similar to the Wilson one.

The following demonstrates:

****************************
* Start Stata code *

* Set up sample
clear
set obs 27
gen event = _n <= 14

* CI by methods already discussed
ci event , bin
ci event , wilson bin

* Set up sampling structure
gen id = 1
replace id = _n
gen pop = 140
svyset id , fpc(pop)

* CI with FPC
svy : proportion  event

* CI without FPC
svyset id 
svy : proportion  event

****************************
* End Stata code *
****************************

Paul T Seed, Senior Lecturer in Medical Statistics, 
Division of Women's Health, King's College London
Women's Health Academic Centre, King's Health Partners 
(+44) (0) 20 7188 3642.


*********************************************
> On Wed, Feb 6, 2013 at 8:53 PM, Ilian, Henry (ACS)
> <Henry.Ilian@dfa.state.ny.us> wrote:
>> The sample size 1s 27, which is the largest number the case readers can handle in the amount of time allotted. The population the sample is drawn from is 140. To get a confidence interval for proportion I used Lenth's on-line application, http://homepage.cs.uiowa.edu/~rlenth/Power/. Since the items have different proportions, there are several confidence intervals. Using 50% as the proportion (meaning that for a particular item, 50% of the sample were awarded the highest ordinal rating, and the other 50% were awarded other ratings), I got a margin of error of 17.3%. For a proportion of 70%, the margin of error is 16%, etc.



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