In: Statistics and Probability
Suppose that the random variable Y1,...,Yn satisfy Yi = ?xi + ?i i=1,...,n. where the set of xi are fixed constants and ?i are iid random variables following a normal distributions of mean zero and variance ?2.
?a (with a hat on it) = ?i=1nYi xi / ?i=1nx2i is unbiased estimator for ?.
The variance is ?a (with a hat on it) = ?2/ ?i=1nx2i . What is the distribation of this variance?