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JWBK119-10
Process Capability of Case2
Using Box-Cox Transformation With Lambda = −2
USL
Process Data transformed data Within
LSL Overall
Target
USL 75.00000 Potential (Within) Capability
Sample Mean 19.40348 Cp
CPL
Sample N 100
StDev (Within) 2.73096 CPU 1.25
1.25
Cpk
StDev (Overall) 2.73096
CCpk 1.25
After Transformation
LSL Overall Capability
Target Pp
USL 0.00018 PPL
Sample Mean 0.00280 PPU 1.25
StDev (Within) 0.00070 Ppk 1.25
StDev (Overall) 0.00070 Cpm
0.00075 0.00150 0.00225 0.00300 0.00375 0.00450
Observed Performance Exp. Within Performance Exp. Overall Performance
PPM < LSL PPM > LSL PPM > LSL
PPM > USL 0.00 PPM < USL 90.61 PPM < USL 90.61
PPM Total 0.00 PPM Total 90.61 PPM Total 90.61
Figure 10.12 Process capability of Case Study 2 using Box--Cox transformation method.
Probability Plot for Case2
LSXY Estimates-Complete Data
3-Parameter Weibull 2-Parameter Exponential
99.9 99.9
90 90
50 50
Percent 10 Percent 10

1 1

0.1 0.1
0.1 1.0 10.0 0.001 0.010 0.100 1.000 10.000 100.000
Case2 - Threshold Case2 - Threshold
3-Parameter Lognormal 3-Parameter Loglogistic
99.9 99.9
99
99
90 90
Percent 50 Percent 50

10 10
1
1
0.1 0.1
2 5 10 20 1 10
Case2 - Threshold Case2 - Threshold
Goodness-of-Fit
Anderson-Darling Correlation
Distribution (adj) Coefficient
3-Parameter Weibull 0.480 0.995
2-Parameter Exponential 14.282
3-Parameter Lognormal 0.237 0.999
3-Parameter Loglogistic 0.295 0.998

Figure 10.13 Probability plot and goodness-of-fit statistics.

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