Statistical Thinking, 3rd Edition

CHAPTER 5Holistic Improvement: Tactics to Deploy Statistical Thinking

To produce quality, you must have a system to improve it.

—Thomas A. Edison

In this chapter, we discuss statistical thinking in greater detail and illustrate three detailed and specific frameworks to apply the statistical thinking strategy presented in Chapter 1. These are certainly not the only possible frameworks, but they are broadly applicable and illustrate the types of tactical approaches needed to apply the statistical thinking strategy to real problems. The first framework emphasizes problem-solving, and is intended to address outliers due to special causes, or situations where “something broke,” and needs to be fixed. Such work results in the process being returned to its normal level of performance, and stabilized.

The second framework is for true process improvement, in which we need to take the process to a new, higher level of performance, not just return it to normal. Such improvement typically requires us to identify the key systematic sources of variation, and then manipulate these variables in such a way as to improve the output. Since systematic sources of variation can be identified and used to predict, they provide a means to obtain true improvement. The third framework is for addressing large, complex, unstructured problems; those for which we may not even be clear on the exact problem to be addressed. Statistical engineering, introduced in Chapter 3, provides a framework for addressing ...