Variable sample size of exponentially weighted moving average chart with measurement errors

Several researchers have investigated the eect of measurement errors on adaptive Shewhart charts. However, the eect of measurement errors on the performance of Variable Sample Size Exponentially Weighted Moving Average (VSS EWMA) control charts has not been evaluated yet. In this regard, the present study aims to investigate the performance of the VSS EWMA chart in the presence of measurement errors using a linear covariate error model and Markov chain method. The results indicated that the presence of measurement errors could signicantly aect the performance of the VSS EWMA chart. In addition, the eect of taking multiple measurements for each item in a subgroup on the performance of the VSS EWMA chart was evaluated. Moreover, the performance of the VSS EWMA control chart was compared with those of several other control charts in the presence of measurement errors. Finally, an illustrative example was presented to demonstrate the application of the VSS EWMA control chart with measurement errors.