So I'm revising my stats by doing a past exam paper, and I'm stuck on one of the questions about unbiased estimators. The question goes...
Suppose that , ,..., are a random sample from a population with mean and variance .
a) Prove that the mean estimator is unbiased for . State carefully any formulae you use.
b) Prove that has variance . State carefully any formulae you use.
It's probably really simple like the last unbiased estimator Q I posted a while back, but I'm just stumped.