| Summary: | 碩士 === 國立交通大學 === 工業工程與管理系所 === 93 === Pearn et al. (1998) introduced the process accuracy index to measure the degree of process centering (the ability to cluster around the center). In this paper, we derive an explicit form for the cumulative distribution function of the estimator . Subsequently, the distributional and inferential properties of the estimated process accuracy index are provided. Calculations of the critical values, p-values, and lower confidence bounds are developed for testing process accuracy. Further, a generalization of for cases with asymmetric tolerances is proposed to measure the process accuracy. The distributional properties of the corresponding natural estimator are investigated. Based on the results practitioners can easily perform the process accuracy testing, and make reliable decisions on whether actions should be taken to improve the process quality. Three application examples are given to illustrate how we test process accuracy using the actual data collected from the factory.
|
|---|
