Question 1: A Strange Way of Estimating the Mean (2 Points)
Usually, we estimate a population mean with the sample mean: ̄X = 1/n ∑ Xi (where each Xi is an independently and identically distributed observation from the population, where E(Xi) = ̄μX and Var(Xi) = σX²). In class, we derived the expectation and variance of ̄X. Another (admittedly strange) way of estimating the population mean would be to add a little noise to the sample mean. Specifically, let the random variable Z ~ N(0, 1). Then define the "franken-mean" to be
ẍ = [1/n ∑ Xi] + Z = ̄X + Z
Assume that Z is independent of all the Xi.
a. Calculate E(ẍ) and Var(ẍ).
b. Is ẍ an unbiased estimator of μX?
c. Is ẍ a consistent estimator of μX?
d. Is ẍ an efficient estimator of μX?