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
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