 An effective joint X-bar and R chart to monitor the process mean and varianceD.R. Prajapati and P.B. Mahapatra International Journal of Productivity and Quality Management, 2007, vol. 2, issue 4, 459-474 Abstract: When the shift occurs in both sample mean and standard deviation of a process, a joint X-bar and R charts can be used to monitor the process mean and variance. This paper deals with very simple and effective design of proposed X-bar and R charts to monitor the process mean and standard deviation. The concept of the proposed chart is based upon the sum of chi-square (χ²) to compute and compare Average Run Length values (ARLs). Although Variable Sample Size (VSS), Variable Sampling Interval (VSI) and Variable Sample Size and Sampling Interval (VSSI) joint charts are very useful to catch the small shifts in the mean or standard deviation, they make the chart more complex and very difficult to use at shop-floor level. The performance of the proposed chart has been compared with VSS, VSI and VSSI joint schemes proposed by Costa (1999). Keywords: average run length; ARL; chi-square max; VSS; VSI; VSSI joint schemes; X-bar charts; R charts; control charts; SPC; statistical process control; variable sample size; variable sampling interval; process monitoring; process mean; variance; productivity; quality management; qaulity control. (search for similar items in EconPapers) Downloads: (external link) Related works: Export reference: BibTeX RIS (EndNote, ProCite, RefMan) HTML/Text Persistent link: https://EconPapers.repec.org/RePEc:ids:ijpqma:v:2:y:2007:i:4:p:459-474 Access Statistics for this article More articles in International Journal of Productivity and Quality Management from Inderscience Enterprises Ltd |
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