Economic-statistical design of EWMA-semicircle charts under the Taguchi loss function Online publication date: Fri, 19-Jul-2019
by Shin-Li Lu
European J. of Industrial Engineering (EJIE), Vol. 13, No. 4, 2019
Abstract: A single exponentially weighted moving average (EWMA) chart is effectively used to monitor the process mean and/or variance simultaneously. An EWMA-semicircle (EWMA-SC) chart designed from the economic-statistical perspective is proposed, which incorporates Taguchi's quadratic loss function into Lorenzen and Vance's cost model. Moreover, economic-statistical performance and the effect on process capability index are compared to those with sum of square EWMA (SS-EWMA) and maximum EWMA (MaxEWMA) charts. The optimal decision variables - namely, sample size n, sampling interval time h, control limit width L and smoothing constant λ - are obtained by minimising the expected cost function. Via simulations, the EWMA-SC chart is found to incur the smallest expected cost when a process mean and variance simultaneously shift. However, the MaxEWMA chart incurs the lowest cost of defective products when a process means shifts on its own. [Received: 1 May 2017; Revised: 22 August 2018; Accepted: 3 January 2019]
Existing subscribers:
Go to Inderscience Online Journals to access the Full Text of this article.
If you are not a subscriber and you just want to read the full contents of this article, buy online access here.Complimentary Subscribers, Editors or Members of the Editorial Board of the European J. of Industrial Engineering (EJIE):
Login with your Inderscience username and password:
Want to subscribe?
A subscription gives you complete access to all articles in the current issue, as well as to all articles in the previous three years (where applicable). See our Orders page to subscribe.
If you still need assistance, please email subs@inderscience.com