T Control Chart with Double Warning Lines
نویسندگان
چکیده
Recent studies have shown that the 2 T control chart with variable sampling intervals (VSI) and/or variable sample sizes (VSS) detects process shifts faster than the traditional 2 T chart. This article extends these studies for processes that are monitored with VSI and VSS using double warning lines ( DWL T − 2 ). It is assumed that the length of time the process remains in control has exponential distribution. The properties of DWL T − 2 chart are obtained using Markov chains. The results show that the DWL T − 2 chart is quicker than VSI and/or VSS charts in detecting almost all shifts in the process mean.
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