Variable sampling interval Shewhart control charts for monitoring the multivariate coefficient of variation. (1st August 2019)

• Record Type: Journal Article
• Authors: Nguyen, Quoc Thong; Tran, Kim Phuc; Heuchenne, Henri L.; Nguyen, Thi Hien; Nguyen, Huu Du
• Is Part Of: Applied stochastic models in business and industry. Volume 35:Number 5(2019)
• Page Start: 1253
• Page End: 1268
• Publication Date: 2019-08-01
• Subjects: average time to signal (ATS) -- multivariate coefficient of variation -- unknown shift size -- variable sampling interval; Stochastic analysis -- Periodicals; Stochastic processes -- Periodicals; Business mathematics -- Periodicals; Finance -- Mathematical models -- Periodicals; Industrial management -- Mathematical models -- Periodicals; 338.00151923
• DOI: 10.1002/asmb.2472
• Languages: English
• ISSNs: 1524-1904

Abstract

Abstract: In many industrial manufacturing processes, the ratio of the variance to the mean of a quantity of interest is an important characteristic to ensure the quality of the processes. This ratio is called the coefficient of variation (CV). A lot of control charts have been designed for monitoring the CV of univariate quantity in the literature. However, the CV control charts for multivariate quantity have not received much attention yet. In this paper, we investigate a variable sampling interval (VSI) Shewhart control chart for monitoring multivariate CV. The time between two consecutive samples is allowed to vary according to the previous value of the multivariate CV, which will help the chart to detect the process shifts faster. The comparison with the fixed sampling interval Shewhart chart is implemented to highlight the advantage of the VSI method. Finally, an illustrative example is demonstrated on real data.