power simulation

---

Graphical Depiction of Power

library(ggplot2)
library(manipulate)
mu0 = 30
myplot <- function(sigma, mua, n, alpha){
    g = ggplot(data.frame(mu = c(27, 36)), aes(x = mu))
    g = g + stat_function(fun=dnorm, geom = "line", 
                          args = list(mean = mu0, sd = sigma / sqrt(n)), 
                          size = 2, col = "red")
    g = g + stat_function(fun=dnorm, geom = "line", 
                          args = list(mean = mua, sd = sigma / sqrt(n)), 
                          size = 2, col = "blue")
    xitc = mu0 + qnorm(1 - alpha) * sigma / sqrt(n)
    g = g + geom_vline(xintercept=xitc, size = 3)
    g
}
manipulate(
    myplot(sigma, mua, n, alpha),
    sigma = slider(1, 10, step = 1, initial = 4),
    mua = slider(30, 35, step = 1, initial = 32),
    n = slider(1, 50, step = 1, initial = 16),
    alpha = slider(0.01, 0.1, step = 0.01, initial = 0.05)
    )