R Code for Power Example from Lecture 22

lecture22.R

coin.power <- function(a, p, n){
  c <-  qnorm(1 - a/2)  
  mu <- sqrt(n) * (2 * p - 1)   
  sigma <- sqrt(4 * p * (1 - p))
  
  less.than <- pnorm( -c, mean = mu, sd = sigma)
  greater.than <- 1 - pnorm(c, mean = mu, sd = sigma)
  power <- less.than + greater.than
  return(power)
}

coin.power(a = 0.05, p = 0.55, n = 100)
coin.power(a = 0.05, p = 0.55, n = 1000)
coin.power(a = 0.1, p = 0.55, n = 100)
coin.power(a = 0.05, p = 0.6, n = 100)


alternatives <- seq(from = 0, to = 1, by = 0.001)
power <- coin.power(a = 0.05, alternatives, n = 10)
plot(alternatives, power, xlab = 'True p', ylab = 'Power', type = 'l')