[R] qbeta function in R

[David Winsemius]

On Mar 9, 2012, at 2:48 PM, Anamika Chaudhuri wrote:

> HI All:
>
> Does anyone know the code behind the qbeta function in R?

Well, yes, but don't you think it would be wise to question whether  
your code might be the problem rather than the R code?

> I am using it to calculate exact confidence intervals and I am getting
> 'NaN' at places I shouldnt be. Heres the simple code I am using:
>
> k<-3
>> x<-NULL
>> p<-rbeta(k,3,3)# so that the mean nausea rate is alpha/(alpha+beta)
>> min<-10
>> max<-60
>> n<-as.integer(runif(3,min,max))
>> for(i in 1:k)
> + x<-cbind(x,rbinom(5,n[i],p[i]))

Isn't this going to make x get longer with each pass through the loop?  
I think your parameter are then going to be interpreted as values of  
"x". Looks like "user error" to me.

-- 
David


>>
>> # Exact Confidence Interval
>>
>> l_cl_exact<-qbeta(.025, x, n-x+1)
> Warning message:
> In qbeta(p, shape1, shape2, lower.tail, log.p) : NaNs produced
>> u_cl_exact<-qbeta(.975, x+1, n-x)
> Warning message:
> In qbeta(p, shape1, shape2, lower.tail, log.p) : NaNs produced
>> x
>     [,1] [,2] [,3]
> [1,]    8   12   14
> [2,]    5   15   13
> [3,]    5   12   12
> [4,]    8   21   12
> [5,]    8   14   12
>> n
> [1] 10 36 31
>> l_cl_exact
>           [,1]      [,2]      [,3]
> [1,] 0.44390454 0.2184996 0.2314244
> [2,] 0.04667766       NaN 0.2454760
> [3,] 0.05452433 0.1855618       NaN
> [4,] 0.44390454 0.4862702 0.1855618
> [5,] 0.10115053       NaN 0.2184996
>
> Thanks for your help.
> Anamika
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at r-project.org 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.

David Winsemius, MD
West Hartford, CT