A Moving Average Control Chart For The Sample Mean Based On A Robust Estimator Of Scale

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Date
2009-04
Authors
Jamel, Suffiah
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Abstract
Lately, the use of quality control charts is becoming more important. Many industries have given increased emphasis on using control charts, such as the Shewhart charts in the monitoring of manufacturing processes. In this area, however, there are still many aspects that need to be extended, generalized and improved upon. The traditional Shewhart control charts are easily affected by occasional outliers that might be a natural part of a process. The limits of these charts are easily stretched by the presence of outliers, making them insensitive in the detection of any out-of-control signal. A robust moving average (MA1oR) chart will be proposed in this dissertation to overcome this problem. The performance of the proposed chart is compared with that of the conventional moving average (MA) chart for the process mean using a simulation study. A moving average control chart is a time weighted chart based on a simple, unweighted moving average of interest, where the chart's statistics incorporates past sample points. The simulation study shows that the proposed MAIQR control chart provides superior results to that of the conventional MA chart in the detection of outliers and other forms of out-of-control situations when outliers are present. Vlll
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Keywords
Mathematics , Quality control -- Charts, diagrams, etc
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