[R] , Exact Confidence Interval

Rui Barradas rui1174 at sapo.pt
Thu Mar 8 01:34:45 CET 2012


Hello,


Anamika Chaudhuri-2 wrote
> 
>>
>> Hi All:
>>
>> I am using R to calculate exact 95% confidence interval using Clopper
>> Pearson method. I am using the following code but it seems to get into a
>> loop and not get out of it, it goes on forever although I am looping it
>> only 10 times across 63 sites with 10 observations per site. I was hoping
>> to get some help.
>>
>> Thanks
>>
> Anamika
> 
>> set.seed(111)  #so that you can regenerate the same values
>> # another time if you need to
>> k<-63
>> n<-10
>> x<-NULL
>> eta<-rnorm(63,-0.085,.990)  # generating data using Binomial Logit Normal
>> p<-exp(eta)/(1+exp(eta))
>> for(i in 1:k)
>> x<-cbind(x,rbinom(10,n,p[i]))
>>
>> rate<-t(t(x)/n)
>>
>> # Exact Confidence Interval
>>
>> for (i in 1:10){
>>
>> for (j in 1:63)
>> {
>>
>> if (x==0)
>> {
>> l_cl_exact<-0
>> u_cl_exact<-qbeta(.975,x+1,n-x)
>> }
>> else if (x==n)
>> {
>> l_cl_exact<-qbeta(.025,x,n-x+1)
>> u_cl_exact<-1
>> }
>> else
>> l_cl_exact<-qbeta(.025,x,n-x+1)
>> u_cl_exact<-qbeta(.975,x+1,n-x)
>>
>> }
>> }_____________________________________________
>> R-help@ mailing list
>> https://stat.ethz.ch/mailman/listinfo/r-help
>> PLEASE do read the posting guide
>> http://www.R-project.org/posting-guide.html<http://www.r-project.org/posting-guide.html>
>> and provide commented, minimal, self-contained, reproducible code.
>>
> 
> 	[[alternative HTML version deleted]]
> 
> ______________________________________________
> R-help@ mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
> 

See package 'binom'. Function 'binom.confint' gives a choice of 8 different
methods,
Clopper-Pearson is the 'exact', and function 'binom.test' also uses it.

Hope this helps,

Rui Barradas


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