Index Terms-Average run length (ARL), exponentially weighted moving average (EWMA) chart, synthetic chart, standard deviation of the run length (SDRL). however, in terms of the SDRL, the EWMA chart surpasses the synthetic chart for small and moderate shifts. the ARL results indicate that the EWMA chart is superior to the synthetic chart for detecting small mean shifts, but the latter prevails for detecting moderate and large shifts. The mathematica programs are used to compute the ARLs and SDRLs of the EWMA and synthetic charts.
comparisons are made based on the normality assumption. this paper compares the average run length (ARL) and standard deviation of the run length (SDRL) profiles of the EWMA and synthetic charts. Since both the EWMA and synthetic charts provide better process mean shifts detection performance, a study on which chart to use in process monitoring under different situations is the aim of this work. control chart for detecting shifts in the process mean. both the exponentially weighted moving average (EWMA) and synthetic charts outperform the shewhart.
the shewhart control chart was the first chart proposed in the literature of SPC and it is still used in process monitoring in today's manufacturing and service industries. The control chart is a valuable tool in SPC. Statistical process control (SPC) techniques are applied to monitor a process. The paper was completed while the writer was working at Stanford University under the auspices of the Office of Naval Research. Greggory of Stanford University for their criticism and suggestions in preparation of this paper. Numerical examples of optimum design are studied to see how variation in the various risk and cost factors affects the optimum.* The writer is greatly indebted to I. The criterion is for the case in which it is assumed that the process is not shut down while the search for the assignable cause is in progress, nor is the cost of adjustment or repair and the cost of bringing the process back into a state of control after the assignable cause is discovered charged to the control chart program.The paper shows how to determine the sample size, the interval between samples, and the control limits that will yield approximately maximum average net income. The quality control rule assumed is that an assignable cause is looked for whenever a point falls outside the control limits. This paper establishes a criterion that measures approximately the average net income of a process under surveillance of an X chart when the process is subject to random shifts in the process mean.
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