Suppose X1, . . . , Xn are i.i.d. random variables having a N (μ, σ2) distribution.
Consider the estimator of σ2, σ2
c = c
nX
i=1
(Xi − ̄X)2. Recall that ˆσ2
c is the MLE if c = 1/n and is the unbiased estimator S2 if c = 1/(n − 1). a) Calculate the mean squared error of ˆσ2
c .
(b) For which value of c is the mean squared error the smallest?