P-value function of prop.test

pvalfun_prop.R

set.seed(1234)
n <- 20
x <- rbinom(1,n,0.5)
print(x)

probbeta <- function(p,x,n){
  ahat <- x + .5
  bhat <- n - x + .5
  pl <- pbeta(p, ahat, bhat, lower.tail=TRUE)
  pu <- pbeta(p, ahat, bhat, lower.tail=FALSE)
  2*pmin(pl,pu)
}

z <- seq(0.01, 0.99, by=0.005)
pv_p <- sapply(z, function(p)prop.test(x, n, p = p, correct = FALSE)$p.value)
pv_b <- sapply(z, function(p)binom.test(x, n, p = p)$p.value)

p_beta <- probbeta(z,x,n)

library(ggplot2)
ggplot(data = NULL)+
  geom_line(aes(x=z, y=pv_p, colour="score test", linetype = "score test"))+
  geom_line(aes(x=z, y=pv_b, colour="binomial test", linetype = "binomial test"))+
  geom_line(aes(x=z, y=p_beta, colour="Bayesian (conjugate beta prior)", linetype = "Bayesian (conjugate beta prior)"))+
  scale_color_brewer(palette = "Set2")+
  theme_bw(16)+theme(legend.position = "bottom")+
  labs(x="param.", y="p-value", colour="method", linetype="method")
ggsave("proptest.png")