Binaryworld - ArrayStdDev - The standard deviation of a numeric array ... [ VB -> Arrays ]

' The standard deviation of an array of any type
'
' if the second argument is True or omitted,
' it evaluates the standard deviation of a sample,
' if it is False it evaluates the standard deviation of a population
'
' if the third argument is True or omitted, Empty values aren't accounted for

Function ArrayStdDev(arr As Variant, Optional SampleStdDev As Boolean = True, _
  Optional IgnoreEmpty As Boolean = True) As Double
  Dim sum As Double
  Dim sumSquare As Double
  Dim value As Double
  Dim count As Long
  Dim index As Long

  ' evaluate sum of values
  ' if arr isn't an array, the following statement raises an error
  For index = LBound(arr) To UBound(arr)
    value = arr(index)
    ' skip over non-numeric values
    If IsNumeric(value) Then
      ' skip over empty values, if requested
      If Not (IgnoreEmpty And IsEmpty(value)) Then
        ' add to the running total
        count = count + 1
        sum = sum + value
        sumSquare = sumSquare + value * value
      End If
     End If
  Next

  ' evaluate the result
  ' use (Count-1) if evaluating the standard deviation of a sample
  If SampleStdDev Then
    ArrayStdDev = Sqr((sumSquare - (sum * sum / count)) / (count - 1))
  Else
    ArrayStdDev = Sqr((sumSquare - (sum * sum / count)) / count)
  End If

End Function