The paper introduces a general framework for testing hypotheses about the structure of the mean function of complex functional processes. Important particular cases of the proposed framework are: 1) testing the null hypotheses that the mean of a functional process is parametric against a nonparametric alternative; and 2) testing the null hypothesis that the means of two possibly correlated functional processes are equal or differ by only a simple parametric function. A global pseudo likelihood ratio test is proposed and its asymptotic distribution is derived. The size and power properties of the test are confirmed in realistic simulation scenarios. Finite sample power results indicate that the proposed test is much more powerful than competing alternatives. Methods are applied to testing the equality between the means of normalized δ-power of sleep electroencephalograms of subjects with sleep-disordered breathing and matched controls.
Staicu, Ana-Maria; Li, Yingxing; Crainiceanu, Ciprian; and Ruppert, David M., "LIKELIHOOD RATIO TESTS FOR THE MEAN STRUCTURE OF CORRELATED FUNCTIONAL PROCESSES" (November 2012). Johns Hopkins University, Dept. of Biostatistics Working Papers. Working Paper 242.