pausa <- function() { cat ("\n >> press Enter to continue\n"); scan() }

model = "tmp_model.bug"
write("
model{
    x0 ~ dbin(p, n0);
    x1 ~ dbin(p, n1);
     p ~ dbeta(1, 1);   
}
", model)

library(rjags)

data = list(n0=20, x0=10, n1=10)   

jm <- jags.model(model, data)
chain <- coda.samples(jm, c("p", "x1"), n.iter=10000)

plot(chain)
print(summary(chain))

p  <- as.vector(chain[[1]][,1])
x1 <- as.vector(chain[[1]][,2])

pausa()

plot(x1,p, col='blue', main=sprintf("cor(p,x1) = %.2f", cor(p,x1) ))
print( table(x1)/10000 )