|α||Probability of a type I error|
|β||Probability of a type II error|
|Standard deviation of sample mean|
|σ||Process standard deviation|
|n||Subgroup or sample size|
We have discussed at length the importance of satisfying the customer by improving the product or service. A process capable of meeting or exceeding customer requirements is a key part of this endeavor. Part III of the book deals with the topic of process control and improvement. It provides the necessary background for understanding statistical process control through control charts. In this chapter we build the foundation for using control charts. The objectives of this chapter are to introduce the principles on which control charts are based. The basic features of the control charts, along with the possible inferential errors and how they may be reduced, are presented. Various types of out-of-control patterns are also discussed. In Chapter 7 we examine control ...