The case against the use of synthetic control charts
Publication date
2017-11-21
Document type
Forschungsartikel
Author
Organisational unit
Scopus ID
Publisher
Taylor & Francis
Series or journal
Journal of Quality Technology
ISSN
Periodical volume
48
Periodical issue
2
First page
178
Last page
195
Part of the university bibliography
✅
Language
English
Keyword
Conditional and cyclical steady-state average run length
Conditional expected delay
Markov chain
Numerical solution of integral equations
Runs rules
Zero-state average run length
Abstract
The synthetic chart principle proposed by Wu and Spedding (2000) initiated a stream of publications in the control charting literature. Originally, it was claimed that the new chart has superior average run length (ARL) properties. Davis and Woodall (2002) indicated that the synthetic chart is nothing else than a particular runs-rule chart. Moreover, they criticized the design of the performance evaluation and advocated use of the steady-state ARL. The latter measure was used then, e.g., in Wu et al. (2010). In most of the papers on synthetic charts that actually used the steady-state framework, it was not rigorously described. See Khoo et al. (2011) as an exception, where it was revealed that the cyclical steady-state design was considered. The aim of this paper is to carefully analyze the steady-state (cyclical and the more popular conditional) for the synthetic chart, the original "2 of L + 1" (L ≥ 1) runs-rule chart, and competing EWMA charts with two types of control limits. It turns out that the EWMA chart has a uniformly (over a large range of potential shifts) better steady-state ARL performance than the synthetic chart. Furthermore, the synthetic control chart exhibits the poorest performance among all considered competitors. Thus, we advise not applying synthetic control charts.
Version
Published version
Access right on openHSU
Metadata only access