In this paper improved Shewhart control charts based on hybrid adaptive and run rules schemes have been introduced to enhance the statistical performances of the traditional static scheme, designed considering fixed values of sample size, width of control limits and sampling frequency. The proposed hybrid adaptive schemes consider both variable sampling interval and variable sample size combined with runs rules. The objective of this research is to develop a statistical comparison between adaptive schemes, charts with run rules and hybrid adaptive schemes with run rules to help the decision makers in the selection of the most performing chart for an expected value of the shift in the mean of the controlled parameter. An extensive set of numerical results is presented to test the effectiveness of the proposed models in detecting small and moderate shifts in the process mean. The optimal statistical designs of the charts are obtained through a heuristic algorithm, properly modified to cope with the problem.
|Titolo:||Statistical design of variable sample size and sampling interval Xbar control charts with run rules|
|Data di pubblicazione:||2006|
|Appare nelle tipologie:||1.1 Articolo in rivista|