Theory of Statistics

Suppose Y1, . .., Yn are i.i.d. Poisson(A). Consider the testing problem: Ho : 1 = do VS H1 : 1 / do. the log-likelihood ratio statistic is given by -2 log A(Y) = 2n (do - A) - Alog (do/ A) , where A = _; Yi. Using Taylor expansion, prove the Wilk's phenomenon directly: -2log >(Y) -+d X3