Two Improved Process Capability Indices

• Main Authors: Chiun-Haw Chou, 周君豪
• Other Authors: Hui-Nien Hung
• Format: Others
• Language: en_US
• Published: 2001
• Online Access: http://ndltd.ncl.edu.tw/handle/60001978684336889463

碩士 === 國立交通大學 === 統計所 === 89 === A new measure of the process capability, $C^{*}$, that takes into account the distance between the target value and mean as well as the process variation is proposed for assessing the process performance. When the target value is equal to the process mean, $C^{*}$ is the same as Cpk. We derive the density of C* by partitioning the domain of \hat{mu} into three parts. The expected values of $\hat{C}^{*}$ and $\hat{C}_{pk}$ under large sample assumption and mu=T>M, where M is the midpoint of the two specification limits, are accounted. Then, another improvement of Cpk, C**, is proposed. Also, we compare the expected values of $\hat{C}^{**}$ and $\hat{C}_{pk}$ under large sample assumption and mu=T>M. Finally, we apply bootstrap methods to give the confidence intervals for C* and C** and compare their lengths with Cpk in the particular case.