Cumulative Sun Control Chart (CUSUM)

Cumulative Sun Control Chart (CUSUM) - A control chart on which the plotted value is the cumulative sum of deviations of successive samples from a target value. The ordinate of each plotted point represents the algebraic sum of the previous ordinate and the most recent deviations from the target.

[Category=Quality ]

Source: American Society for Quality, 16 September 2010 10:35:23, http://www.asq.org/glossary/

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CUSUM Chart - A cusum chart is a type of control chart (cumulative sum control chart). It is used to detect small changes between 0-0.5 sigma. For larger shifts (0.5-2.5), Shewart-type charts are just as good and easier to use. Cusum charts plot the cumulative sum of the deviations between each data point (a sample average) and a reference value, T. Unlike other control charts, one studying a cusum chart will be concerned with the slope of the plotted line, not just the distance between plotted points and the centerline. Critical limits for a cusum chart are not fixed or parallel. And a mask in the shape of a V is usually laid over the chart with the origin over the last plotted point. Previous points covered by the mask indicate the process has shifted.

So, who uses these types of charts? Typically chemical industries.

[Category=Data Quality ]

Source: iSixSigma, 13 January 2011 08:52:14, https:web.archive.org/web/20111109014246/http:www.isixsigma.com/index.php?option=com_glossary