'Topic_17.sbs
'Calculates the means of specified samples
'Written by M Miller for Mth 110 and Mth 111 at Le Moyne
'Last revised 27-Oct-2006

Sub main
	Sample_Size = 1
	Number_of_Samples = 200
    Variable = "age"

    Set Document = objSpssApp.Documents
	Set DataDoc = Document.GetDataDoc(0)
    Population_Size = DataDoc.GetNumberOfCases

    'This is a kludge to create the variable SampleMeans.
    objSpssApp.ExecuteCommands "Compute SampleMeans = 0.", True
	objSpssApp.ExecuteCommands "Execute.", True
	DataDoc.SelectCells("SampleMeans", "SampleMeans", 1, Population_Size)
	DataDoc.Clear

    'Read in the values of Variable
    Values = DataDoc.GetTextData (Variable, Variable, 1, Population_Size)

    'This array tracks of the values used, so they don't get re-sampled.
    Dim Used()
    ReDim Used (0 To Population_Size)
    Used(0) = 1 'If Rnd=0 then CInt rounds 0.5 to 0 so K=0;
                'this excludes that (very rare) case.

	For I = 1 To Number_of_Samples

        For J = 1 To Population_Size
           Used(J) = 0
        Next J

        'Calculate the mean of a random sample, sampling without replacement.
        Sum = 0
		For J = 1 To Sample_Size
			K = 0
            While Used(K) = 1
               K = CInt(Population_Size*Rnd + 0.5) 'Rounds to nearest integer.
            Wend
            Used(K) = 1
            Sum = Sum + CSng(Values(0, K-1)) 'Values is a 0-based array.
		Next J
        Mean = Sum/Sample_Size

        'Copy the mean to the clipboard, then paste into the ith cell.
        Clipboard CStr(Mean)
		DataDoc.SelectCells ("SampleMeans", "SampleMeans", i, i)
		DataDoc.Paste

	Next I
End Sub