Enhancing the Power of Process Control by Utilizing Auxiliary Information in Profiles

• Main Authors: Hsiang-Ling Huang, 黃香菱
• Other Authors: Jyh-Jen Horng Shiau
• Format: Others
• Language: en_US
• Published: 2008
• Online Access: http://ndltd.ncl.edu.tw/handle/35514072793052511190

碩士 === 國立交通大學 === 統計學研究所 === 96 === Traditional control charting methods in statistical process control monitor the quality characteristic of the product or process of interest directly. Now thanks to well-developed technologies, we can easily record many other related data that may provide additional information about the quality characteristic at different time points. For example, we can record the quality response variable along the time before the end product is finished. If we regard the record of these values as the profile of a product item, then the quality characteristic of the end product is the endpoint of the profile. It is natural to expect that this auxiliary information would be able to help enhancing the control process. In this study, we focus on Phase II monitoring. Our approach is to fit each profile by parametric or nonparametric regression methods, and then monitor the fitted endpoint value instead of the endpoint response. It can be shown that, with the additional profiles information, the fitted endpoint response has smaller variance than the endpoint response itself. Accordingly, when compared to the traditional approach, better detecting power can be achieved with the proposed approach