Remedial Measures to Lessen the Effect of Imprecise Measurement on the Performance of the MAX-EWMAMS

What is it about?

Simultaneous monitoring of process mean and variability by a single control chart has been increasingly taken into consideration in recent years. However, the effect of imprecise measurements on the performances of some existing control schemes has been neglected. In this paper, the effect of measurement errors with linearly increasing variance on the detecting and diagnosing capability of the MAX-EWMAMS control chart is first investigated in Phase II monitoring. The results obtained using simulation show that the measurement errors affect the two performances of the chart, significantly. Then, two remedial measures including the ranked set sampling (RSS) approach and using a larger sample size are proposed. The simulation results confirm that both the remedial measures compensate for the effect of measurement errors, adequately. A real data example is also used to illustrate the effect of measurement errors on the rate of false alarm.

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