Combined Shewhart-cusum control chart for improved quality control in clinical chemistry.

Westgard, James O.; Groth, Torgny; Aronsson, T.; Verdier, C.-H. De

doi:10.1093/clinchem/23.10.1881

Cited by 115 publications

(29 citation statements)

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“…It is hard to find the application of the runs rules schemes with the CUSUM charts in the literature. However, Westgard et al 12 studied some control rules using combined Shewhart–CUSUM structures. They proved superiority of this combined approach on the separate Shewhart's approach but ignored any comparison with the separate CUSUM application.…”

Section: Cusum Chartsmentioning

confidence: 99%

Improving the performance of CUSUM charts

Riaz

Does

2011

Quality & Reliability Eng

100

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Improving the performance of CUSUM chartsRiaz, M.; Abbas, N.; Does, R.J.M.M. General rightsIt is not permitted to download or to forward/distribute the text or part of it without the consent of the author(s) and/or copyright holder(s), other than for strictly personal, individual use, unless the work is under an open content license (like Creative Commons). Disclaimer/Complaints regulationsIf you believe that digital publication of certain material infringes any of your rights or (privacy) interests, please let the Library know, stating your reasons. In case of a legitimate complaint, the Library will make the material inaccessible and/or remove it from the website. Please Ask the Library: http://uba.uva.nl/en/contact, or a letter to: Library of the University of Amsterdam, Secretariat, Singel 425, 1012 WP Amsterdam, The Netherlands. You will be contacted as soon as possible. The control chart is an important statistical technique that is used to monitor the quality of a process. Shewhart control charts are used to detect larger disturbances in the process parameters, whereas CUSUM and EWMA charts are meant for smaller and moderate changes. Runs rules schemes are generally used to enhance the performance of Shewhart control charts. In this study, we propose two runs rules schemes for the CUSUM charts. The performance of these two schemes is compared with the usual CUSUM, the weighted CUSUM, the fast initial response CUSUM and the usual EWMA schemes. The comparisons revealed that the proposed schemes perform better for small and moderate shifts, whereas they reasonably maintain their efficiency for large shifts as well.

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Section: Cusum Chartsmentioning

confidence: 99%

Improving the performance of CUSUM charts

Riaz

Does

2011

Quality & Reliability Eng

100

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“…Specifically we can rewrite scheme (2.5) as N = min(N I , N 2 ) , where N, is Page's likelihood CUSUM scheme (2.3) with fl = fo· More generally, if we have k control schemes represented by stopping times T l , • J • • , Ti ; where T, is the time at which an out-of-control signal is triggered because of a significant departure of type j from the state of statistical control, then we can combine these k schemes into a composite scheme T=min(TI> ... , T k ) . Westgard et al (1977) and Lucas (1982) used this idea to combine the two-sided CUSUM scheme (2.5) with a two-sided Shewhart scheme so that the 'combined Shewhart-CUSUM chart' can detect more quickly than the CUSUM scheme (2.5) departures from 0 that are larger than lOll and O 2 ,…”

Section: Combined Shewhart-cumulative Sum Charts and Other Composite mentioning

confidence: 99%

Sequential Changepoint Detection in Quality Control and Dynamical Systems

Lai

1995

Journal of the Royal Statistical Society Series B: Statistical Methodology

419

287

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SUMMARY After a brief survey of a large variety of sequential detection procedures that are widely scattered in statistical references on quality control and engineering references on fault detection and signal processing, we study some open problems concerning these procedures and introduce a unified theory of sequential changepoint detection. This theory leads to a class of sequential detection rules which are not too demanding in computational and memory requirements for on‐line implementation and yet are nearly optimal under several performance criteria.

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“…As L + and S+ occupy the positive half of the plot, and L -and S-the negative this does not lead to the 'chart clutter' one might expect. In addition, with a suitable choice of scale the U, can be superimposed on the cusum charts and used as a Shewhart chart for location and spread (as in Westgard et al, 1977). The use of U, to control for scale is an alternative to the proposal by Nelson (1982) to use the absolute value of successive differences, and has the advantage of using what is a better estimator of location while the process is under control.…”

Section: Lii=lo=sii=so=omentioning

confidence: 99%

Self-Starting Cusum Charts for Location and Scale

Hawkins¹

1987

The Statistician

181

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In some quality control problems, it is not known what the exact process mean and standard deviation are under control but it is desired to determine whether there have been drifts from the conditions obtained at the process start-up. This situation is not well-covered by standard cumulative sum procedures, which generally assume known process parameters. This paper uses the running mean and standard deviation of all observations made on the process since start-up as substitutes for the unknown true values of the process mean and standard deviation. Using some theoretical properties of independence of residuals, two pairs of cusums are set up: one testing for constancy of location of the process, and the other for constancy of the spread. While the process is under control, both these cusum pairs are of approximately normal N(O, I) quantities (and therefore are well understood), but if the location, the spread or both change, then non-centrality is introduced into one or both of the location and scale cusum pairs, and it drifts out-of-control. It is shown that the procedure performs well in detecting changes in the process, even in comparison with the often utopian situation in which the process mean and variance are known exactly prior to the start of the cusum..

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Combined Shewhart-cusum control chart for improved quality control in clinical chemistry.

Cited by 115 publications

References 0 publications

Improving the performance of CUSUM charts

Improving the performance of CUSUM charts

Sequential Changepoint Detection in Quality Control and Dynamical Systems

Self-Starting Cusum Charts for Location and Scale

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