The Treatment of Six Sigma in Introductory Operations Management Textbooks: Clearing Up the Confusion

This paper critically examines the treatment of the statistical basis for Six Sigma and process capability in popular operations management textbooks. It discusses areas of confusion and suggest ways of treating the topic that make sense to instructors as well as students. Even though Six Sigma was introduced almost 30 years ago, misconceptions persist. In the textbooks we have found no consistency of approach or understanding of the statistical underpinnings (3.4 defects per million opportunities) of Six Sigma. Sometimes statements are made that are factually incorrect and cause frustration for students and instructors. Similar difficulties are encountered in discussions of the related concept of process capability. The paper suggests changes that will help resolve these issues and bring much-needed clarity to discussions of these important ideas. Students will find the material much more accessible and instructors will find it much easier to convey the concepts underlying this important topic.