Two-Sample Test for Sparse High Dimensional Multinomial Distributions

Abstract: In this paper we consider testing the equality of probability vectors of two independent multinomial distributions in high dimension. The classical chi-square test may have some drawbacks in this case since many of cell counts may be zero or may not be large enough. We propose a new test and show its asymptotic normality and the asymptotic power function. Based on the asymptotic power function, we present an application of our result to neighborhood type test which has been previously studied, especially for the case of fairly small $p$-values. To compare the proposed test with existing tests, we provide numerical studies including simulations and real data examples.