Title: Chapter 17 Introduction
Course: Canvas Practice Course

KEY CONCEPTS

This chapter presents a brief history of the steps that led to America accepting statistical process control. It also is an introduction to statistical process control and focuses on statistics that answer the following questions:

- Where are the values centered (what is the average)?
- How spread out are the values (what is the range of values)?
- Are there any changes in the values over time?

Tabular displays of data often do not provide a ready appreciation of many of the important characteristics of a collection of data. Large numbers of observations are best displayed in a frequency table or histogram that present a distribution in pictorial form. Histograms are bar charts of the values from a data set grouped into classes. Histograms give good estimates of what populations look like (shape), how much spread there is, and where they are centered.

Processes that are stable and predictable have a fixed pattern of variation that can be described by a mathematical curve. This predictable pattern is known as the normal distribution and is a smooth curve that has a particular shape that resembles a bell and is often called a bell curve. The normal distribution statistics reveals a 99.7% certainty that a measurement will fall between ± 3 swhen a normal distribution is present.