Statistical Methods for Quality Improvement, Third Edition

CHAPTER 10

Miscellaneous Control Chart Topics

In this chapter we discuss several topics that, although important, would generally not be presented in individual chapters. These include pre-control, short-run SPC, charting autocorrelated data, nonparametric control chart approaches, Bayesian control chart methods, the economic design of control charts, administrative applications of control charts, software for control charting, and applications of control charts in specific industries and for specific company functions.

10.1 PRE-CONTROL

This topic is presented first in this chapter, not because of its importance but rather because many companies seem to have used it. Bhote (1991), Shainin (1984), Shainin and Shainin (1989), and others have claimed that pre-control is a superior alternative to control charts, and there is evidence (Bhote, 1988) that Motorola has used pre-control extensively. We will examine these claims and also discuss critical assessments of pre-control that have appeared in the literature (Ledolter and Swersey, 1997), as well as consider the properties of suggested modifications to pre-control. The properties of these modified procedures have been studied by Steiner (1997).

The first paper on pre-control was a technical report by Satterthwaite (1954). Pre-control was originally advocated for machining operations, for which an operator has to set up a machine and then determine whether or not the setup was performed properly. The contention has been that it is ...