On the gap between theory and practice of process capability studies

Historically, a theoretical framework has been established to judge whether a process is capable or not. These studies, called process capability studies, have received both positive and negative comments. Both researchers and practitioners have indicated that the concept of process capability studies is often misused in practice. This article aims to identify and quantify this misuse, and when it is severe, try to provide some explanations of its origin. The survey presented is primarily based on questionnaires and carried out among 97 Swedish organisations where process capability studies are used regularly. It shows that there is often a gap between theory and practice concerning process capability studies. The article also provides some possible answers to why the gap exists. It has been found that the gap between theory and practice can be explained by management issues, practical problems, conservative personal attitudes and methodological aspects. Based on the results, some suggestions for successfully implementing and using process capability studies are presented.