1. (a) What does reproducible calculations and reproducible simulations refer to and when or why should the calculations/simulations be reproducible?

(b) When is it a sensible strategy to use the Gaussian model in a simulation? When is it not and why? (Hint. Your answer could contain an illustrative example.)

(c) Consider a random sample of observations X = [X1, . . . , Xn]. Why would we expect that, typically, the variables of the sample X are correlated, but the principal component scores obtained from these variables are not?