Problem 3: A confidence interval for Poisson distributions
Let X1, Xn be iid Poisson random variables with parameter λ > 0, and denote by Xn their empirical average: X.
Find two sequences (an) and (bn) such that (an(Xn - bn)) converges in distribution to a standard Gaussian random variable Z ~ N(0,1).
Prove that for all t > 0, P(|Z| < t) = 2P(Z < t) - 1.
Using the previous questions, find an interval T centered around Xn such that P(T ≤ Xn) ≥ 0.95, as n approaches infinity. [Hint: The 97.5%-quantile of the standard Gaussian distribution is 1.96.]
Modify the previous interval T in order to get a new interval J that is not necessarily centered around Xn, does not depend on λ, and such that P(J) ≥ 0.05, as n approaches infinity.