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caballerov's avatar
caballerov
Regular Visitor
2 years ago
Solved

Calculating PPK values in PowerBI vs Minitab - Need help.

I am encountering inconsistencies between Power BI and Minitab when calculating the PPK value, despite using the identical data set. While the PPL value calculations align in both software, the PPU a...
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  • caballerov's avatar
    caballerov
    2 years ago

    For anyone trying to figure this out, I was able to get the same PPK result as Minitab by calculating the Sigma and Mean values by filtering the data within the limits.

     

    I created new Measures for both:

    Sigma Within Limits =
    CALCULATE(
        STDEV.S(Data[Net(g)]),
        FILTER(
            Data,
            Data[Net(g)] >= LSL[LSL Value] &&
            Data[Net(g)] <= USL[USL Value]
        )
    )
     
    Mean Within Limits =
    AVERAGEX(
        FILTER(
            Data,
            Data[Net(g)] >= LSL[LSL Value] &&
            Data[Net(g)] <= USL[USL Value]
        ),
        Data[Net(g)]
    )
     
    PPU Within Limits = (USL[USL Value] - [Mean Within Limits]) / (3 * [Sigma Within Limits])
    PPL Within Limits = ([Mean Within Limits] - LSL[LSL Value]) / (3 * [Sigma Within Limits])
     
    PPK Within Limits = MIN([PPU Within Limits], [PPL Within Limits])
caballerov's avatar
caballerov
Regular Visitor
2 years ago

For anyone trying to figure this out, I was able to get the same PPK result as Minitab by calculating the Sigma and Mean values by filtering the data within the limits.

 

I created new Measures for both:

Sigma Within Limits =
CALCULATE(
    STDEV.S(Data[Net(g)]),
    FILTER(
        Data,
        Data[Net(g)] >= LSL[LSL Value] &&
        Data[Net(g)] <= USL[USL Value]
    )
)
 
Mean Within Limits =
AVERAGEX(
    FILTER(
        Data,
        Data[Net(g)] >= LSL[LSL Value] &&
        Data[Net(g)] <= USL[USL Value]
    ),
    Data[Net(g)]
)
 
PPU Within Limits = (USL[USL Value] - [Mean Within Limits]) / (3 * [Sigma Within Limits])
PPL Within Limits = ([Mean Within Limits] - LSL[LSL Value]) / (3 * [Sigma Within Limits])
 
PPK Within Limits = MIN([PPU Within Limits], [PPL Within Limits])