Sending Custom Statistics to Statistica in VB.NET

Public Class StatsMgr

'a custom exception for any member function to throw if 'it can not calculate results for any reason

Public Class BadResults Inherits System.Exception 'note the ability to inherit base classes

Dim ErrMessage As String

End Class

'retrieves the sum of the specified variable of 'the specified spreadsheet

Function Sum(ByVal Spr As Statistica.Spreadsheet, _ ByVal VarNo As Long) As Double

Dim i As Long Dim TotalVal As Double = 0

For i = 1 To Spr.NumberOfCases

'ignore missing data If Spr.SelectionCondition.Evaluate(i) And _ Not (Spr.MissingData(i, VarNo)) Then

TotalVal = TotalVal + Spr.Value(i, VarNo)

End If

Next i

Sum = TotalVal

End Function

'retrieves the number of valid observations Function ValidObs(ByVal Spr As Statistica.Spreadsheet, _ ByVal VarNo As Long) As Double

Dim TotalValid As Long = 0 Dim i As Long

For i = 1 To Spr.NumberOfCases

'ignore missing data and make sure case selections allow its inclusion If Not (Spr.MissingData(i, VarNo)) And Spr.SelectionCondition.Evaluate(i) Then

TotalValid = TotalValid + 1

End If

Next i

ValidObs = TotalValid

End Function

'retrieves the variance of a variable Function Variance(ByVal Spr As Statistica.Spreadsheet, _ ByVal VarNo As Long) As Double

Dim Total As Double Dim N As Long Dim Mean As Double Dim SumOfSquares As Double

SumOfSquares = 0 Total = Sum(Spr, VarNo) N = ValidObs(Spr, VarNo)

'if there aren't any valid observations then thow an error If Total = 0 Or N < 2 Then

Throw New StatsMgr.BadResults()

End If

Mean = Total / N

Dim i As Long

For i = 1 To Spr.NumberOfCases

If Spr.SelectionCondition.Evaluate(i) And _ Not (Spr.MissingData(i, VarNo)) Then

'calculate squares of differences 'iterate through each case, subtract the means from it, and then 'square it.  Add all of these up and you will have the sum of squares. SumOfSquares = SumOfSquares + ((Spr.Value(i, VarNo) - Mean) ^ 2)

End If

Next i

Variance = SumOfSquares / (N - 1)

End Function

End Class

Module VBNETCustomStatistics

Sub Main()

'this is the variable that will be analyzed in our dataset Const VARIABLE_TO_ANALYZE As Long = 3

'create a new instance of Statistica Dim StatApp As New Statistica.Application()

StatApp.Visible = True

'open a dataset Dim DataSet As Statistica.Spreadsheet

'also note that you can initialize variables when they 'are declared

Try

'note that you do not need to use "Set" in VB.NET DataSet = StatApp.Spreadsheets.Open(StatApp.Path & _ "\Examples\Datasets\Adstudy.sta", True)

Catch ThisException As System.Runtime.InteropServices.COMException

System.Console.Write(ThisException.ToString()) End

End Try

'create a singleton class to calculate our own custom statistics Dim Statistican As New StatsMgr()

'spreadsheet to hold our custom statistics Dim Results As Statistica.Spreadsheet = StatApp.Spreadsheets.[New]("Descriptive Stats from VB.NET")

Results.SetSize(VARIABLE_TO_ANALYZE, 1) Results.CaseNameWidth = 1 Results.VariableName(1) = "Results" Results.Variable(1).AutoFit() Results.Header.Value = "Results for " & DataSet.Name & ", Variable " & VARIABLE_TO_ANALYZE.ToString 'the Sum case Results.CaseName(1) = "SUM" Results.Case(1).Value = Statistican.Sum(DataSet, VARIABLE_TO_ANALYZE) 'the Valid number of observations case Results.CaseName(2) = "VALID N" Results.Case(2).Value = Statistican.ValidObs(DataSet, VARIABLE_TO_ANALYZE)

'the Variance case Results.CaseName(3) = "VARIANCE"

'our variance function my throw an exception if there are not enough 'valid observations in the given variable

Try

Results.Case(3).Value = Statistican.Variance(DataSet, VARIABLE_TO_ANALYZE)

Catch ThisException As StatsMgr.BadResults

Results.Case(3).Value = "----"

End Try

Results.Visible = True

'clean up StatApp = Nothing Statistican = Nothing

End Sub

End Module