Refactoring: functions

n <- length(x); m <- mean(x); s <- sd(x)
c(m - 1.96 * s / sqrt(n), m + 1.96 * s / sqrt(n))

n <- length(y); m <- mean(y); s <- sd(y)
c(m - 1.96 * s/sqrt(n), m + 1.96 * s/sqrt(n))

# Define a function to prevent pasting the code above
ci <- function(values) {
  n <- length(values)
  m <- ___ 
  s <- ___ 
  c(m - ___, m + ___)
}