Hi hubinho,

You need to initialize the for() loop and then store the u and l values
properly:

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

# creating B 2x2 tables
B <- 50
u <- l <- vector('numeric', B)
for (i in 1:B){
    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))}

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

# coverage
theta <- 1:B
foo <- function(theta, u, l) mean(theta >= l & theta <= u, na.rm = TRUE)
foo(theta, u, l)
#  [1] 0.14

HTH,
Jorge.-


On Mon, Mar 19, 2012 at 2:25 PM, hubinho <> wrote:

> 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)
> }
>
> --
> View this message in context:
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> Sent from the R help mailing list archive at Nabble.com.
>
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>

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