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Imports System
Imports System.Collections
Imports CenterSpace.NMath.Core
Imports System.IO
Namespace CenterSpace.NMath.Core.Examples.VisualBasic
' A .NET example in Visual Basic showing some of the advanced features of class OneWayAnova.
Module AdvancedOneWayAnovaExample
Sub Main()
' 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.
Dim AnovaData As DataFrame = DataFrame.Load("AdvancedOneWayAnovaExample.dat", False, False, " ", True)
' The names of the three groups in the study.
Dim Healthy As String = "Healthy"
Dim NonMelancholic As String = "Nonmelancholic"
Dim Melancholic As String = "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).
Dim Anova As OneWayAnova = New OneWayAnova(AnovaData, 0, 1)
' Print out the means for each of the three groups.
Dim HealthGroupMean As Double = Anova.GetGroupMean(Healthy)
Dim NonMelancholicGroupMean As Double = Anova.GetGroupMean(NonMelancholic)
Dim MelancholicGroupMean As Double = Anova.GetGroupMean(Melancholic)
Console.WriteLine()
Console.WriteLine("Healthy group mean = " & HealthGroupMean.ToString("G7"))
Console.WriteLine("NonMelancholic group mean = " & NonMelancholicGroupMean.ToString("G7"))
Console.WriteLine("Melancholic group mean = " & 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()
Console.WriteLine("Between Groups:")
Console.WriteLine(" Sum of Squares = " & Anova.AnovaTable.SumOfSquaresBetween.ToString("G7"))
Console.WriteLine(" Degrees of Freedom = " & Anova.AnovaTable.DegreesOfFreedomBetween.ToString("G7"))
Console.WriteLine(" Mean Square = " & Anova.AnovaTable.MeanSquareBetween.ToString("G7"))
Console.WriteLine()
Console.WriteLine("Within Groups:")
Console.WriteLine(" Sum of Squares = " & Anova.AnovaTable.SumOfSquaresWithin.ToString("G7"))
Console.WriteLine(" Degrees of Freedom = " & Anova.AnovaTable.DegreesOfFreedomWithin.ToString("G7"))
Console.WriteLine(" Mean Square = " & Anova.AnovaTable.MeanSquareWithin.ToString("G7"))
Console.WriteLine()
Console.WriteLine("Total:")
Console.WriteLine(" Sum of Squares = " & Anova.AnovaTable.SumOfSquaresTotal.ToString("G7"))
Console.WriteLine(" Degrees of Freedom = " & Anova.AnovaTable.DegreesOfFreedomTotal)
Console.WriteLine(" Mean Square = " & Anova.AnovaTable.MeanSquareTotal.ToString("G7"))
Console.WriteLine()
' 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.
Dim F As Double = Anova.AnovaTable.FStatistic
Dim Alpha As Double = 0.01
Dim CriticalValue As Double = Anova.FStatisticCriticalValue(Alpha)
Console.Write("F = ")
Console.WriteLine(F)
Console.WriteLine()
Console.WriteLine("Critical value for alpha < " & Alpha & " = " & CriticalValue.ToString("G5"))
Console.WriteLine()
If (F > CriticalValue) Then
Console.WriteLine("Reject the null hypothesis that the means are the ")
Console.WriteLine("same in all three groups at the " & Alpha & " significance level.")
Else
Console.WriteLine("Accept the null hypothesis that the means are the ")
Console.WriteLine("same in all three groups at the " & Alpha & " significance level.")
End If
Console.WriteLine()
Console.WriteLine("Press Enter Key")
Console.Read()
End Sub
End Module
End 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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