Memorandum 1717

Alternative Shewhart-type charts for grouped observations

W. Albers & W.C.M. Kallenberg

Abstract:
Classical Shewhart control charts based on groups of observations use the average as statistic to decide whether a signal should be produced or not. Here several other statistics are investigated as well. Moreover, individual charts are compared with group charts. The chart using the minimum of each group of observations is a promising new proposal. For this chart (nonparametric) estimation of an extreme quantile is reduced to estimation of an ordinary quantile, which is far easier to perform accurately. The behavior of the minimum-chart is competitive to that of the average-chart when distributions are known.

Keywords:   Statistical process Control, Phase II control limits, order statistics

Mathematics Subject Classification:   62P30, 62C05

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