Visualizing capability and stability on a single chart

Abstract

Clear and simple data visualization is critical when communicating information about a process to less technically oriented personnel. This paper demonstrates that process stability and capability can be conveyed on one plot. Since, location and scale are not the only features of the process that might change when the process leaves control, we consider simple charts that can detect such changes in addition to location and scale. A simulation study demonstrates when and where various control charts might be best at detecting particular out of control conditions. The meaning behind conventional capability indices can be quickly inferred from the proposed tool. The visualization tool is demonstrated on three data-sets.

Keywords:

• R Charts
• Charts
• D charts
• Max Charts
• s Charts
• minimum charts
• maximum charts
• extreme charts
• Process Charts
• specification limits

Acknowledgements

The authors gratefully acknowledge useful comments from two anonymous reviewers which led to a substantial improvement in the manuscript.

Notes

No potential conflict of interest was reported by the authors.

Additional information

Funding

This research was supported by a grant from the University of British Columbia and by Natural Sciences and Engineering Research Council of Canada.