Let \(X_1,X_2,\ldots ,X_n\) be independent, identically distributed random variables with density function \[ h(t;\sigma )=\frac {1}{(2\pi \sigma ^2)^{1/2}} e^{-(t-1)^2/(2\sigma ^2)}. \] We wish to test \(H_0:\sigma =\sigma _0\) against \(H_A:\sigma \ne \sigma _0\).
(a) Find a test, using the generalized likelihood ratio \(\lambda \).
(b) Provide a large sample approximation for \(-2\log \lambda \) under \(H_0\).