Statistical Analysis with R Essentials For Dummies

Chapter 6

Standards, Standings, and Summaries

IN THIS CHAPTER

Catching some Zs

Understanding standard scores in R

Summarizing a data frame

When you compare numbers, context is important. To make valid comparisons across contexts, you often have to convert numbers into standard units. In this chapter, I show you how to use statistics to do just that. Standard units show you where a score stands in relation to other scores within a group. I also show you other ways to determine a score’s standing within a group, and I finish by showing you how to summarize data.

Catching Some Zs

A number in isolation doesn’t provide much information. To fully understand what a number means, you have to take into account the process that produced it. To compare one number to another, they have to be on the same scale.

When you’re converting currency, it’s easy to figure out a standard. When you convert temperatures from Fahrenheit to Celsius, or lengths from feet to meters, a formula guides you.

When it’s not so clear-cut, you can use the mean and standard deviation to standardize scores that come from different processes. The idea is to take a set of scores and use its mean as a zero-point, and ...