title: Efficient Blockwise Permutation Tests Preserving Exchangeability.
abstract: In this paper, we present a new blockwise permutation test approach based on the moments of the test statistic. The method is of importance to neuroimaging studies. In order to preserve the exchangeability condition required in permutation tests, we divide the entire set of data into certain exchangeability blocks. In addition, computationally efficient moments-based permutation tests are performed by approximating the permutation distribution of the test statistic with the Pearson distribution series. This involves the calculation of the first four moments of the permutation distribution within each block and then over the entire set of data. The accuracy and efficiency of the proposed method are demonstrated through simulated experiment on the magnetic resonance imaging (MRI) brain data, specifically the multi-site voxel-based morphometry analysis from structural MRI (sMRI).
authors.affiliation: Mark O. Hatfield Clinical Research Center, National Institutes of Health, Bethesda, MD, USA.
authors.forename: Chunxiao
authors.initials: C
authors.lastname: Zhou
authors.affiliation: Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA.
authors.forename: Chris E
authors.initials: CE
authors.lastname: Zwilling
authors.affiliation: Dept. of ECE, The University of New Mexico, and The Mind Research Network and LBERI, Albuquerque, NM, USA.
authors.forename: Vince D
authors.initials: VD
authors.lastname: Calhoun
authors.affiliation: Department of Psychology, University of Illinois at Urbana-Champaign, Champaign, IL, USA ; Department of Statistics, University of Illinois at Urbana-Champaign, Champaign, IL, USA ; Department of Bioengineering, University of Illinois at Urbana-Champaign, Champaign, IL, USA.
authors.forename: Michelle Y
authors.initials: MY
authors.lastname: Wang
keywords: Efficient nonparametric test; Pearson distribution series; moments; structural MRI; voxel-based morphometry