Standard Deviation

[GingerNut]

What the hell is standard deviation anyway?

Well I wrote a prog to calculate the mean and standard devation of a set of numbers. The mean part was easy enough but I'm having probs with the standard deviation. Here is the code I'm using:

Dim X As Long
Dim SumX1 As Single
Dim SumX2 As Single
Dim NumValues As Integer
 
'Seperate Numbers'
Array1 = Split(txtNumbers.Text, ",")
    
Total = 0
For X = 0 To UBound(Array1)
    Total = Total + Array1(X)
Next X
 
SumX1 = SumX1 + Total
SumX2 = SumX2 + Total ^ 2
NumValues = UBound(Array1) + 1
 
'Calculate and Display Mean
Mean = SumX1 / NumValues
lblMean.Caption = Mean
 
'Calculate and Display Standard Deviation
Stdev = Sqr((NumValues * SumX2 - SumX1 ^ 2) / (NumValues * (NumValues - 1)))
 
lblDeviation.Caption = Stdev

I'm not getting the right answer for the standard deviation. So maybe one of you brainy guys could tell me where I've gone wrong.