ENBIS-8 in Athens

21 – 25 September 2008 Abstract submission: 14 March – 11 August 2008

The r-out-of-m S Control Chart

23 September 2008, 12:00 – 12:20


Submitted by
Athanasios Rakitzis
Antzoulakos D.L. and Rakitzis C.A.
Department of Statistics & Insurance Science, University of Piraeus, Greece
Control charts with supplementary runs rules for detecting shifts in the process variance have not received as much attention as their counterparts for detecting shifts in process average. Monitoring the variance of a manufacturing process is as important as monitoring its average. In this paper we examine the performance of S control charts accompanied with runs rules for monitoring increases or decreases in process variance. The proposed one-sided charts overcome the weakness of high false alarm rates when runs rules are used to supplement a control chart. The average run length performance and the design of the proposed schemes are studied thoroughly. Finally, the performance of appropriately designed two-sided schemes is investigated as well.
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