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Capability calculations for True Position

VinniUSMC
Has anyone come across this as a means of calculating Cpk of a true position?

http://documentation.statsoft.com/ST...tionCapability

I think it should be possible, but I'm not sure if this is the answer or not. I was thinking about how something along the lines of the complex plane (or vectors/trig) could be used to identify grouping of a positional tolerance based on its quadrant within a unit circle, and then could be used to calculate Cpk. It's not unheard of. The normal distribution of a multivariate system is calculable, so why wouldn't a statistic that is related to the normal distribution in 1 variable work for higher dimensions?

I'm thinking that there must be a way to calculate the variance of position based on the the quadrant it falls in. Whether it's a trigonometric function, or a complex function.

Anyone have any input as I dive into this blackhole?

Curiosity killed the cat, hopefully I'm not a cat.

Parents
  • There's a "Macro1" (it's a xlsm file !) : 
    Sub Macro1()
'
' Macro1 Macro
'
Dim aver1, stddev1, angle1, cp, cpk1, cpk2, three_sigma, dist, dist1, dist2
'
For i = 1 To 18
angle1 = (i - 1) * 10
If (i - 1) * 10 = 90 Then
angle1 = 90.000001
End If
Range("L2").Select
ActiveCell.Value = angle1
Range("X3").Select
aver1 = ActiveCell.Value
Range("X4").Select
stddev1 = ActiveCell.Value
Range("T20").Select
dist = ActiveCell.Value
Range("Z4").Select
three_sigma = ActiveCell.Value
Range("V14").Select
dist1 = ActiveCell.Value
Range("V16").Select
dist2 = ActiveCell.Value

cp = dist / three_sigma
cpk1 = dist1 / three_sigma
cpk2 = dist2 / three_sigma


Range("AB" & (i + 6)).Select
ActiveCell.Value = angle1
Range("AC" & (i + 6)).Select
ActiveCell.Value = aver1
Range("AD" & (i + 6)).Select
ActiveCell.Value = stddev1
Range("AE" & (i + 6)).Select
ActiveCell.Value = cp
Range("AF" & (i + 6)).Select
ActiveCell.Value = cpk1
Range("AG" & (i + 6)).Select
ActiveCell.Value = cpk2

Next i
End Sub


    It calculates cp, cpk1 and cpk2 with my understanding of the text ! (so not necessarily as a standard !!!!!!!)
  • in reply to JEFMAN
    Oh, I found it. I think you're probably right, I just only saw the values and so I wasn't sure how the cells were getting those values. Thanks. Slight smile

    Macros are over my head completely. PC-DMIS is the most "coding" that I can do.
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