The Modifications of Process Capability Index Based on The Penalty Ratio

• Main Authors: Ya-Ling Huang, 黃雅伶
• Other Authors: Ching-Ho Leu
• Format: Others
• Language: zh-TW
• Published: 2004
• Online Access: http://ndltd.ncl.edu.tw/handle/48714033374863187634

碩士 === 國立成功大學 === 統計學系碩博士班 === 92 === 　　In recent, Process Capability Index (PCI) has already used in the quality management extensively. The value of PCI can use to decide the capability of the production fit in with the process specifications. In real world, the most popular indices are Cp and Cpk. But these indices still have some defects, especially in asymmetrical specifications. We take a penalty ratio from the ratio of the shift to tolerance to modify the Cp index and Cpk index. We therefore bring up six new indices. The estimators of the new indices and their statistical properties are discussed. We find that the naive estimator can be modified such that the new estimator has smaller bias and MSE. It shows the performances of the new indices don’t tend to extreme and can reflect the real process capability under the symmetrical or asymmetrical specification.