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using System;
using System.IO;
using CenterSpace.NMath.Core;
namespace CenterSpace.NMath.Examples.CSharp
{
/// <summary>
/// A .NET example in C# showing some of the advanced features of class OneWayAnova.
/// </summary>
class AdvancedOneWayAnovaExample
{
static void Main( string[] args )
{
// Construct a DataFrame from the data in the file. The file contains
// data for three groups of people, healthy people, melancholic depressed
// people, and nonmelancholic depressed people. For each of these
// groups the cortisol levels in the blood are measured*
// The data consists of two columns. The first column contains the name
// of the group that an individual belongs to and the second column
// contains the level of cortisol for the individual.
DataFrame anovaData = DataFrame.Load( "AdvancedOneWayAnovaExample.dat", false, false, " ", true );
// The names of the three groups in the study.
string healthy = "Healthy";
string nonMelancholic = "Nonmelancholic";
string melancholic = "Melancholic";
// Construct a OneWayAnova instance from the DataFrame. The first
// integer argument specifies which column contains the group names
// and the second integer argument specifies which column contains
// the numeric data (as zero based indices).
var anova = new OneWayAnova( anovaData, 0, 1 );
// Print out the means for each of the three groups.
double healthGroupMean = anova.GetGroupMean( healthy );
double nonMelancholicGroupMean = anova.GetGroupMean( nonMelancholic );
double melancholicGroupMean = anova.GetGroupMean( melancholic );
Console.WriteLine();
Console.WriteLine( "Healthy group mean = {0}", healthGroupMean.ToString( "G7" ) );
Console.WriteLine( "NonMelancholic group mean = {0}", nonMelancholicGroupMean.ToString( "G7" ) );
Console.WriteLine( "Melancholic group mean = {0}", melancholicGroupMean.ToString( "G7" ) );
// Print out the sum of squares, degrees of freedom and mean square
// for each of the source between groups, within groups, and total.
Console.WriteLine( Environment.NewLine + "Between Groups:" );
Console.WriteLine( " Sum of Squares = {0}", anova.AnovaTable.SumOfSquaresBetween.ToString( "G7" ) );
Console.WriteLine( " Degrees of Freedom = {0}", anova.AnovaTable.DegreesOfFreedomBetween );
Console.WriteLine( " Mean Square = {0}" + Environment.NewLine, anova.AnovaTable.MeanSquareBetween.ToString( "G7" ) );
Console.WriteLine( "Within Groups:" );
Console.WriteLine( " Sum of Squares = {0}", anova.AnovaTable.SumOfSquaresWithin.ToString( "G7" ) );
Console.WriteLine( " Degrees of Freedom = {0}", anova.AnovaTable.DegreesOfFreedomWithin.ToString( "G7" ) );
Console.WriteLine( " Mean Square = {0}" + Environment.NewLine, anova.AnovaTable.MeanSquareWithin.ToString( "G7" ) );
Console.WriteLine( "Total:" );
Console.WriteLine( " Sum of Squares = {0}", anova.AnovaTable.SumOfSquaresTotal.ToString( "G7" ) );
Console.WriteLine( " Degrees of Freedom = {0}", anova.AnovaTable.DegreesOfFreedomTotal );
Console.WriteLine( " Mean Square = {0}" + Environment.NewLine, anova.AnovaTable.MeanSquareTotal.ToString( "G7" ) );
// Fetch the F statistic and the critical value for the F statistic and
// decide whether or not to reject the null hypothesis that all group
// means are the same.
double F = anova.AnovaTable.FStatistic;
double alpha = 0.01;
double criticalValue = anova.FStatisticCriticalValue( alpha );
Console.WriteLine( "F = {0}", F );
Console.WriteLine( "Critical value for alpha < {0} = {1}", alpha, criticalValue.ToString( "G5" ) );
if ( F > criticalValue )
{
Console.WriteLine( "Reject the null hypothesis that the means are the " );
Console.WriteLine( "same in all three groups at the {0} significance level.", alpha );
}
else
{
Console.WriteLine( "Accept the null hypothesis that the means are the " );
Console.WriteLine( "same in all three groups at the {0} significance level.", alpha );
}
Console.WriteLine();
Console.WriteLine( "Press Enter Key" );
Console.Read();
} // Main
} // class
} // namespace
// * Source: L. H. Price, D. S. Charney, A. L. Rubin, and F. R.
// Henniger, "alpha2 Adregenric Receptor Function in Depression:
// The Cortisol Response to Yohimbine," Arch. Gen. Psychiatry
// 43:849-858, 1986.
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