[R] Coverage Probability

hubinho hubinho at hotmail.com
Mon Mar 19 19:25:55 CET 2012


Thank you very much. This was, was i needed. Unfortunately I have one futher
problem with this Code. I don't only need the coverage probability for one
but for a range of different odds ratios. (for example [1;30]). I tried it
with a loop but I get an error. I think again, that I'm almost there but
having a little mistake. The complete code is:

#setting values

n1 <- 10
n2 <- 10
y <- 100
alpha <- 1
z<-1.96

# creating 2x2 table

for (i in 1:30)

{

theta <- i
x1 <- exp(alpha +theta)/ (1+  exp(alpha +theta))
x2 <- exp(alpha)/ (1+  exp(alpha))


n11 <- rbinom(y, 10, x1)
n12 <- n1 - n11
n21 <- rbinom(y, 10, x2)
n22 <- n2 - n21

# upper and lower limit gart interval

gartu <-function(z,d,e, f, g){log(((d+.5)*(g+.5))/((e+.5)*(f+.5)))+
z*sqrt(1/(d+.5)+1/(e+.5)+1/(f+.5)+1/(g+.5))}
gartl <-function(z,d,e, f, g){log(((d+.5)*(g+.5))/((e+.5)*(f+.5)))-
z*sqrt(1/(d+.5)+1/(e+.5)+1/(f+.5)+1/(g+.5))}


u <- gartu(z, n11[i],n22[i],n12[i],n21[i])
l <- gartl(z, n11[i],n22[i],n12[i],n21[i])

foo <- function(theta, u, l) mean(theta >= l & theta <= u, na.rm = TRUE)
 foo(theta, u, l)
}

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