inst/snippet/var01.R

In rpruim/fastR: Foundations and Applications of Statistics Using R (2nd Edition)

x <- 0:2
sum((x - 1)^2 * dbinom(x, 2, 0.5))   # same as above
n <- 5; p <- 0.2; x <- 0:n
sum((x - n*p)^2 * dbinom(x, n, p))     # X ~ Binom(5, 0.2)
n <- 5; p <- 0.8; x <- 0:n
sum((x - n*p)^2 * dbinom(x, n, p))     # X ~ Binom(5, 0.8)
n <- 10; p <- 0.8; x <- 0:n
sum((x - n*p)^2 * dbinom(x, n, p))     # X ~ Binom(10, 0.8)
n <- 20; p <- 0.8; x <- 0:n
sum((x - n*p)^2 * dbinom(x, n, p))     # X ~ Binom(20, 0.8)