Third-order local power properties of tests for a composite hypothesis

This paper addresses, for a composite hypothesis about a subvector of the parameters in the parametric model, the issues posed by Rao and Mukerjee (1995) [22] and Li (2001) [14] on the power under a sequence of local alternatives. It is shown that a partially adjusted test statistic in a class of test statistics is equally sensitive (up to the third-order) to the change of the nuisance parameters. However, there exist infinitely many ways for improving the chi-squared approximation to the null distribution, which reveal, in general, the non-equivalence of the resulting third-order point-by-point local powers. To make a definitive conclusion, the average local power is then considered, from which the third-order asymptotic optimality of the Bartlett-type adjusted Rao test can be also established.