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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13 ## General Public License for more details.
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20 ## @deftypefn {Function File} {[@var{pval}, @var{chisq}, @var{df}] =} mcnemar_test (@var{x})
21 ## For a square contingency table @var{x} of data cross-classified on
22 ## the row and column variables, McNemar's test can be used for testing
23 ## the null hypothesis of symmetry of the classification probabilities.
25 ## Under the null, @var{chisq} is approximately distributed as chisquare
26 ## with @var{df} degrees of freedom.
28 ## The p-value (1 minus the CDF of this distribution at @var{chisq}) is
29 ## returned in @var{pval}.
31 ## If no output argument is given, the p-value of the test is displayed.
34 ## Author: KH <Kurt.Hornik@wu-wien.ac.at>
35 ## Description: McNemar's test for symmetry
37 function [pval, chisq, df] = mcnemar_test (x)
43 if (! (min (size (x)) > 1) && issquare (x))
44 error ("mcnemar_test: X must be a square matrix of size > 1");
45 elseif (! (all (all (x >= 0)) && all (all (x == fix (x)))))
46 error ("mcnemar_test: all entries of X must be non-negative integers");
52 num = max (abs (x - x') - 1, 0) .^ 2;
54 num = abs (x - x') .^ 2;
57 chisq = sum (sum (triu (num ./ (x + x'), 1)));
58 pval = 1 - chi2cdf (chisq, df);
61 printf (" pval: %g\n", pval);