Variable sampling interval Shewhart control charts for monitoring the multivariate coefficient of variation

2019 ◽  
Vol 35 (5) ◽  
pp. 1253-1268 ◽  
Author(s):  
Quoc Thong Nguyen ◽  
Kim Phuc Tran ◽  
Henri L. Heuchenne ◽  
Thi Hien Nguyen ◽  
Huu Du Nguyen
Keyword(s):  
Coefficient Of Variation ◽  
Control Charts ◽  
Sampling Interval ◽  
Shewhart Control Charts ◽  
Variable Sampling Interval ◽  
Variable Sampling ◽  
Shewhart Control ◽  
Multivariate Coefficient Of Variation

Design of a Variable Sampling Interval EWMA Median Control Chart

2019 ◽  
Vol 26 (05) ◽  
pp. 1950021 ◽  
Author(s):  
Kim Phuc Tran ◽  
Philippe Castagliola ◽  
Thi Hien Nguyen ◽  
Anne Cuzol
Keyword(s):  
Control Chart ◽  
Control Charts ◽  
Food Production ◽  
Average Run Length ◽  
Moving Average ◽  
Sampling Interval ◽  
Performance Comparison ◽  
Variable Sampling Interval ◽  
Variable Sampling ◽  
Weighted Moving Average

In the literature, median type control charts have been widely investigated as easy and efficient means to monitor the process mean when observations are from a normal distribution. In this work, a Variable Sampling Interval (VSI) Exponentially Weighted Moving Average (EWMA) median control chart is proposed and studied. The Markov chains are used to calculate the average run length to signal (ARL). A performance comparison with the original EWMA median control chart is made. The numerical results show that the proposed chart is considerably more effective as it is faster in detecting process shifts. Finally, the implementation of the proposed chart is illustrated with an example in food production process.

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