Detecting changes in autoregressive processes withX¯and EWMA charts
作者:
JOHNR. ENGLISH,
SEN-CHIN LEE,
TERRYW. MARTIN,
CHUCK TILMON,
期刊:
IIE Transactions
(Taylor Available online 2000)
卷期:
Volume 32,
issue 12
页码: 1103-1113
ISSN:0740-817X
年代: 2000
DOI:10.1080/07408170008967465
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The traditional use of control charts necessarily assumes the independence of data. It is now recognized that many processes are autocorrelated thus violating the fundamental assumption of independence. As a result, there is a need for a broader approach to SPC when data are time-dependent or autocorrelated. This paper utilizes control charts with fixed control limits for residuals to monitor the performance of a process yielding time-dependent data subject to shifts in the mean and the autocorrelation structure. The effectiveness of the framework is evaluated by an average ran length study of bothX¯and EWMA charts using analytical and simulation techniques. Average run lengths are tabulated for various process disturbance scenarios, and recommendations for the most effective monitoring tool are made. The findings of this research present motivation to extend the traditional paradigms of a shifted process (e.g., mean and/or variance). The results show that decreases in the underlying time series parameters are practically impossible to detect with standard control charts. Furthermore, the practitioner is motivated to employ runs rules since the runs are more likely with time-dependent observations.
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