1 ## Copyright (C) 1996-2012 Kurt Hornik
3 ## This file is part of Octave.
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6 ## under the terms of the GNU General Public License as published by
7 ## the Free Software Foundation; either version 3 of the License, or (at
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20 ## @deftypefn {Function File} {[@var{pval}, @var{tsq}] =} hotelling_test (@var{x}, @var{m})
21 ## For a sample @var{x} from a multivariate normal distribution with unknown
22 ## mean and covariance matrix, test the null hypothesis that @code{mean
23 ## (@var{x}) == @var{m}}.
25 ## Hotelling's @math{T^2} is returned in @var{tsq}. Under the null,
26 ## @math{(n-p) T^2 / (p(n-1))} has an F distribution with @math{p} and
27 ## @math{n-p} degrees of freedom, where @math{n} and @math{p} are the
28 ## numbers of samples and variables, respectively.
30 ## The p-value of the test is returned in @var{pval}.
32 ## If no output argument is given, the p-value of the test is displayed.
35 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
36 ## Description: Test for mean of a multivariate normal
38 function [pval, Tsq] = hotelling_test (x, m)
46 error ("hotelling_test: if X is a vector, M must be a scalar");
53 error ("hotelling_test: X must have more rows than columns");
55 if (isvector (m) && length (m) == p)
56 m = reshape (m, 1, p);
58 error ("hotelling_test: if X is a matrix, M must be a vector of length columns (X)");
61 error ("hotelling_test: X must be a matrix or vector");
65 Tsq = n * d * (cov (x) \ d');
66 pval = 1 - fcdf ((n-p) * Tsq / (p * (n-1)), p, n-p);
69 printf (" pval: %g\n", pval);