The presence of measurement error can seriously affect the outcome of any process and reduces the ability of control charts to detect a shift of a particular magnitude in the process parameters. Research has shown the superiority of exponentially weighted moving average (EWMA) control charts over Shewhart charts when it comes to quick and timely detection of small process shifts. In this study, the performance of the EWMA control chart is examined in the presence of two-component measurement error due to its immense importance in analytical chemistry and environmental settings. It has been shown that effect of measurement error can be reduced by taking multiple measurements at each sample point. (44 refs.)
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