1.II.27I

Principles of Statistics
Part II, 2005

State Wilks' Theorem on the asymptotic distribution of likelihood-ratio test statistics.

Suppose that X1,,XnX_{1}, \ldots, X_{n} are independent with common N(μ,σ2)N\left(\mu, \sigma^{2}\right) distribution, where the parameters μ\mu and σ\sigma are both unknown. Find the likelihood-ratio test statistic for testing H0:μ=0H_{0}: \mu=0 against H1:μH_{1}: \mu unrestricted, and state its (approximate) distribution.

What is the form of the tt-test of H0H_{0} against H1H_{1} ? Explain why for large nn the likelihood-ratio test and the tt-test are nearly the same.