Presenting Your Data
In This Chapter
Using control charts
Looking at different ways to display data
This chapter introduces the importance of understanding and identifying variation. If you can identify what type of variation you’re seeing in your process results, you can determine whether action is needed or not, and avoid taking inappropriate action and wasting effort.
Control charts can be used to identify types of variation in your process and in the various materials, goods, and parts coming into your process, for example. This chapter covers how to use these powerful data displays. We focus on the most commonly used type, the X moving R, or individuals and range, control chart.
Later in the chapter we refer to some other data displays and ways to assess variation, looking at histograms and hypothesis tests.
Delving into Different Types of Variation
Things are seldom exactly the same, even if at first glance they appear to be so. Variation exists in people’s heights, in the many shades of the colour green, in the number of words in each sentence of this book and in the time different people take to read this book.