近幾年來，製程能力指標被製造業廣泛的應用在品質監控方面，用以評估製程能力是否符合水準。一般而言，這些廠商僅利用樣本來推估製程能力指標並不是一種精確的估計方式，甚至可能因為抽樣的誤差造成製程能力錯誤的估算。此外，文獻上製程能力指標往往侷限於單一品質特性的製程能力分析，但在實務上，產品通常具有多項品質特性，因此，如何對多項品質特性的產品進行製程能力分析，儼然成為一個重要的課題。本研究利用複式模擬法的概念將標準誤一同考慮在區間估計中，並根據C”pm多品質製程能力分析圖來監控同時擁有望目型、望大型及望小型三種不同品質特型的多品質特性產品。以提供廠商與顧客一個簡單且有效率的評估方法並作為未來合約或判斷產品製程優劣的依據。

In recent years, process capability indices (PCI’s) have been wildly applied in the quality monitoring by most manufacturing industry. They are used to assess the ability of a manufacturing process whether is capable or not. However, it is insufficient for manufacture to measure whether the process meets the PCI’s just by using the estimator. Since point estimator may seriously result in misestimating to PCI’s due to sampling bias, thus, in this study we use the bootstrap method to construct a confidence interval. By sampling with replacement, we construct a confidence interval based on standard error of point estimator.
Besides, most studies associated with analyzing the quality and efficiency of PCI’s are limited to one single quality specification. In practical, a product is usually composed of numerical quality characteristics. Hence, in this study, we use bootstrap method to estimate process capability indices, and construct C”pm multiple process performance analysis chart to determine whether the PCI’s of the multi-characteristics product meets the preset target. We anticipate that this study will provide a simple and efficient method as a criterion for measuring process capability of a product.

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