mean(y) = 74 sd(y) = 17.19173
## 표준점수 zy = (y - mean(y)) / sd(y) = (y - 74) / 17.19173
m = colMeans(x) = (74, 63.6, 80.9) s = apply(x,2,sd) = (17.19173, 13.56630, 11.45474)
xm = matrix(1,10,1) %*% m
xs = matrix(1,10,1) %*% s
- 표준점수 zx = (x - xm) / xs
xm = matrix(1,10,1) %*% m
xs = matrix(1,10,1) %*% s
zx = (x - xm) / xs