| Summary: | 碩士 === 淡江大學 === 統計學系碩士班 === 95 === In recent years, Process Capability Indices (PCIs) have been applied in the quality control by most practitioners, to evaluate the capability of a production process. However, the approach of these practitioners usually simply look at the index value calculated from the given sample and then making a decision on whether the given process is capable or not is intuitively reasonable but not reliable because sampling errors are ignored. Therefore, the confidence interval approach should be provided to decide whether the production process is capable or not.
For comparing two processes, we consider to estimates the ratio and the difference of two capability indices Cpmk. For point estimation, the bias and the mean square error (MSE) of the given point estimation method are simulated and compared. With respect to the confidence interval estimation, we use the Boyles(1991) method, three bootstrap methods, and the Jackknife method to construct the confidence interval of the ratio of two Cpmk indices. Furthermore, we use the Chen and Hsu’s(1995) method, three bootstrap methods, and the Jackknife method to estimate the difference of two Cpmk indices. The samples generated from normal distribution are used for simulation study and the performance of all methods based the highest average probability are evaluated. At least, one example is given to demonstrate how to compare two processes by using all proposed methods.
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