Performance Evaluation of Control Schemes Under Drift in Simple Linear Profiles

摘要

Sometimes, quality of a process is characterized by a relationship between two variables referred to as profile. So far, several methods have been proposed for monitoring simple linear profiles. In all of the researches, the performance of the proposed methods is only investigated under step shifts. However, the other types of shifts such as drift can occur in the process and control charts should detect them as well. In this paper, phase II monitoring of simple linear profiles is investigated and the performance of more popular methods in the literature including T2, EWMA-R, and EWMA-3 is evaluated under drift shift. Average run length criterion is used for this purpose. The results show that the EWMA-3 method roughly performs better than the other methods. It is roughly similar to the results obtained under the step shifts.