Evaluation Of Bootstrap Confidence Intervals Using A New Non-Normal Process Capability Index

Abstract: This paper assesses the bootstrap confidence intervals of a newly proposed process capability

index (PCI) forWeibull distribution, using the logarithm of the analyzed data. These methods can

be applied when the quality of interest has non-symmetrical distribution. Bootstrap confidence

intervals, which consist of standard bootstrap (SB), percentile bootstrap (PB), and bias-corrected

percentile bootstrap (BCPB) confidence interval are constructed for the proposed method. A Monte

Carlo simulation study is used to determine the eciency of newly proposed index Cpkw over the

existing method by addressing the coverage probabilities and average widths. The outcome shows

that the BCPB confidence interval is recommended. The methodology of the proposed index has

been explained by using the real data of breaking stress of carbon fibers.

Keywords: non-normal process capability index; bootstrap confidence intervals; average width;

coverage probabilities;Weibull distribution

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