x <- c(0,1,2,3,4,5)
n <- c(70,70,70,70,70,70)
z <- c( 0, 9,21,47,60,63)
y <- n - z
b <- cbind(y, z)
fitx <- glm(b ~ x, family=binomial)
print(fitx)
plot(x,y/n,xlim=c(0,5),ylim=c(0,1),ylab="")
beta0 <- fitx$coef[1]
beta1 <- fitx$coef[2]
fn <- function(x) exp(beta0+beta1*x)/(1+exp(beta0+beta1*x))
par(new=T)
curve(fn,0,5,ylim=c(0,1),ylab="Propn surviving")