Chapter 18: Statistical Process Control

This chapter is entitled "Statistical Process Control," or SPC. This topic is often the most dreaded of all subjects when discussing process improvement. Why? Because it involves numbers, and then scrutinizing the numbers to determine whether the numbers are correctly collected, reported, and used throughout the organization. Many organizations will collect metrics "because the book says we have to in order to get our rating." Well, I have to admit that is a good reason, but it is not the best reason. When used correctly, metrics can help decision makers make good decisions. When used incorrectly, they can help decision makers justify their mistakes. Metrics can also be used by managers to abuse their people. So, this chapter spends a lot of time discussing metrics and the data that go into them.

It would be absurd to think that one small chapter in this book could teach you all about SPC. What we have tried to do in this book is to distill the knowledge you need to implement process improvement activities in your organization. So, this chapter also tries to do that; that is, to summarize what can sometimes be difficult concepts into something you can use right away. We have tried to summarize the information we have learned over the years and to summarize the best practices we have found in other organizations.

This chapter introduces different types of charts and discusses reasons for using the charts and reasons for collecting data. You will not be an...