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// Accord Statistics Library
// The Accord.NET Framework
// http://accord-framework.net
//
// Copyright © César Souza, 2009-2017
// cesarsouza at gmail.com
//
// This library is free software; you can redistribute it and/or
// modify it under the terms of the GNU Lesser General Public
// License as published by the Free Software Foundation; either
// version 2.1 of the License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
//
namespace Accord.Statistics.Testing
{
using System;
using Accord.Statistics.Analysis;
using Accord.Compat;
/// <summary>
/// Bowker test of symmetry for contingency tables.
/// </summary>
///
/// <remarks>
/// <para>
/// This is a <see cref="ChiSquareTest">Chi-square kind of test</see>.</para>
/// </remarks>
///
/// <seealso cref="ChiSquareTest"/>
///
[Serializable]
public class BowkerTest : ChiSquareTest
{
/// <summary>
/// Creates a new Bowker test.
/// </summary>
///
/// <param name="matrix">The contingency table to test.</param>
///
public BowkerTest(GeneralConfusionMatrix matrix)
{
int classes = matrix.NumberOfClasses;
int[,] n = matrix.Matrix;
double Qb = 0;
for (int j = 0; j < classes; j++)
{
for (int i = 0; i < j; i++)
{
double q = (n[i, j] - n[j, i]);
Qb += (q * q) / (n[i, j] + n[j, i]);
}
}
int df = (classes * (classes - 1)) / 2;
Compute(Qb, df);
}
}
}