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Daniel S. T. Hughes > Statistics-MVA-Bartlett-0.0.4 > Statistics::MVA::Bartlett



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Statistics::MVA::Bartlett - Multivariate Test of Equality of Population Covariance Matrices.


This document describes Statistics::MVA::Bartlett version 0.0.4


    # we have several groups of data each with 3 variables
    my $data_X = [
        [qw/ 191 131 53/],
        [qw/ 200 137 52/],
        [qw/ 173 127 50/],
        [qw/ 160 118 47/],
        [qw/ 188 134 54/],
        [qw/ 186 129 51/],
        [qw/ 163 115 47/],

    my $data_Y = [
        [qw/ 211 122 49/],
        [qw/ 201 144 47/],
        [qw/ 242 131 54/],
        [qw/ 184 108 43/],
        [qw/ 223 127 51/],
        [qw/ 208 125 50/],
        [qw/ 199 124 46/],
    my $data_Z = [
        [qw/ 185 134 50/],
        [qw/ 171 128 49/],
        [qw/ 174 131 52/],
        [qw/ 186 107 49/],
        [qw/ 211 118 51/],
        [qw/ 217 122 49/],

    use Statistics::MVA::Bartlett;
    # Create a Statistics::MVA::Bartlett object and pass it the data as a series of Lists-of-Lists within an anonymous array. 
    my $bart1 = Statistics::MVA::Bartlett->new([$data_X, $data_Y, $data_Z]);

    # Access the output using the bartlett_mva method. In void context it prints a report to STDOUT.

    # In LIST-context it returns the relevant parameters.
    my ($chi, $df, $p) = $bart->bartlett_mva;


Bartlett's test is used to test if k samples have equal variances. This multivariate form tests for homogeneity of the variance-covariance matrices across samples. Some statistical tests assume such homogeneity across groups or samples. This test allows you to check that assumption. See


'Statistics::MVA' => '0.0.1', 'Carp' => '1.08', 'Math::Cephes' => '0.47', 'Statistics::Distributions' => '1.02',


Let me know.


Daniel S. T. Hughes <>


Copyright (c) 2010, Daniel S. T. Hughes <>. All rights reserved.

This module is free software; you can redistribute it and/or modify it under the same terms as Perl itself. See perlartistic.


Because this software is licensed free of charge, there is no warranty for the software, to the extent permitted by applicable law. Except when otherwise stated in writing the copyright holders and/or other parties provide the software "as is" without warranty of any kind, either expressed or implied, including, but not limited to, the implied warranties of merchantability and fitness for a particular purpose. The entire risk as to the quality and performance of the software is with you. Should the software prove defective, you assume the cost of all necessary servicing, repair, or correction.

In no event unless required by applicable law or agreed to in writing will any copyright holder, or any other party who may modify and/or redistribute the software as permitted by the above licence, be liable to you for damages, including any general, special, incidental, or consequential damages arising out of the use or inability to use the software (including but not limited to loss of data or data being rendered inaccurate or losses sustained by you or third parties or a failure of the software to operate with any other software), even if such holder or other party has been advised of the possibility of such damages.

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