Data Analysis Mathematics Linear Algebra Statistics
New Version 7.0!  QuickStart Samples

# Repeated Measures Anova QuickStart Sample (Visual Basic)

Illustrates how to use the OneWayRAnovaModel class to perform a one-way analysis of variance with repeated measures in Visual Basic.

```Option Infer On

Imports Extreme.DataAnalysis
Imports Extreme.Statistics

Namespace Extreme.Numerics.QuickStart.VB
' Illustrates the use of the OneWayRAnovaModel class for performing
' a one-way analysis of variance with repeated measures.
Module AnovaRepeatedMeasuresWay

Sub Main()
' This QuickStart Sample investigates the effect of the color of packages
' on the sales of the product. The data comes from 12 stores.
' Packages can be either red, green or blue.

' Set up the data as anonymous records
Dim data = {
New With {.Person = 1, .Drug = 1, .Score = 30},
New With {.Person = 1, .Drug = 2, .Score = 28},
New With {.Person = 1, .Drug = 3, .Score = 16},
New With {.Person = 1, .Drug = 4, .Score = 34},
New With {.Person = 2, .Drug = 1, .Score = 14},
New With {.Person = 2, .Drug = 2, .Score = 18},
New With {.Person = 2, .Drug = 3, .Score = 10},
New With {.Person = 2, .Drug = 4, .Score = 22},
New With {.Person = 3, .Drug = 1, .Score = 24},
New With {.Person = 3, .Drug = 2, .Score = 20},
New With {.Person = 3, .Drug = 3, .Score = 18},
New With {.Person = 3, .Drug = 4, .Score = 30},
New With {.Person = 4, .Drug = 1, .Score = 38},
New With {.Person = 4, .Drug = 2, .Score = 34},
New With {.Person = 4, .Drug = 3, .Score = 20},
New With {.Person = 4, .Drug = 4, .Score = 44},
New With {.Person = 5, .Drug = 1, .Score = 26},
New With {.Person = 5, .Drug = 2, .Score = 28},
New With {.Person = 5, .Drug = 3, .Score = 14},
New With {.Person = 5, .Drug = 4, .Score = 30}}
Dim frame = DataFrame.FromObjects(data)

' Construct the OneWayAnova object.
Dim anova = New OneWayRAnovaModel(frame, "Score", "Drug", "Person")
' Alternatively, we can use a formula to specify the variables
' in the model
anova = New OneWayRAnovaModel(frame, "Score ~ Drug + Person")

' Perform the calculation.
anova.Compute()

' Verify that the design is balanced:
If (Not anova.IsBalanced) Then
Console.WriteLine("The design is not balanced.")
End If

' The AnovaTable property gives us a classic anova table.
' We can write the table directly to the console:
Console.WriteLine(anova.AnovaTable.ToString())
Console.WriteLine()

' A Cell object represents the data in a cell of the model,
' i.e. the data related to one level of the factor.
' We can use it to access the group means for each drug.

' We need two indices here: the second index corresponds
' to the person factor.

' First we get the IIndex object so we can easily iterate
' through the levels:
Dim drugFactor = anova.GetFactor(Of Integer)(0)
For Each level In drugFactor
Console.WriteLine("Mean for group '{0}': {1:F4}",
level, anova.TreatmentTotals.Get(level).Mean)
Next

' We could have accessed the cells directly as well:
Console.WriteLine("Variance for second drug: {0}",
anova.TreatmentTotals.Get(2).Variance)
Console.WriteLine()

' We can get the summary data for the entire model
' by using the TotalCell property:
Dim totalSummary As Cell = anova.TotalCell
Console.WriteLine("Summary data:")
Console.WriteLine("# observations: {0}", totalSummary.Count)
Console.WriteLine("Grand mean:     {0:F4}", totalSummary.Mean)

Console.WriteLine("Press Enter key to continue.")