Some Thoughts on Obtaining Prediction Intervals and Creating Control Charts for Process Capability Indices

This paper will take a deeper look at the four basic process capability indices. It will describe the indices, their estimates, their uses and drawbacks, and, finally, it will attempt to create prediction intervals for future index readings based upon previous readings. Control charting, which does not seem to have been addressed for capability indices in the literature, will be presented. In addition, the process of finding prediction intervals has resulted in some alternate derivations for the confidence limits presented by Chou, Owen, and Borrego, and these derivations will also be discussed