Statistical Analysis with R For Dummies

Chapter 4

Finding Your Center

IN THIS CHAPTER

Working within your means

Meeting conditions

Understanding that the median is the message

Getting into the mode

If you’ve ever worked with a set of numbers and had to figure out how to summarize them with a single number, you’ve faced a situation that statisticians deal with all the time. Where would this ideal “single number” come from?

A good idea might be to select a number from somewhere in the middle of the set. That number could then represent the entire set of numbers. When you’re looking around in the middle of the set, you’re looking at central tendency. You can address central tendency in a variety of ways.

Means: The Lure of Averages

We’ve all used averages. Statisticians refer to the average as the mean. The mean is an easy way to summarize your spending, your school grades, your performance in a sport over time.

In the course of their work, scientists calculate means. When a researcher does a study, she applies some kind of treatment or procedure to a small sample of people or things. Then she measures the results and estimates ...