## Chapter 4. Probability

**4.1** Events

**4.2** More Definitions

**4.3** Some Rules of Probability

**4.4** Assigning Probabilities

One-Minute Summary

Test Yourself

Probability theory serves as one of the building blocks for inferential statistics. This chapter reviews the probability concepts necessary to comprehend the statistical methods discussed in later chapters. If you are already familiar with probability, you should skim this chapter to learn the vocabulary that this book uses to discuss probability concepts.

### 4.1 Events

Events underlie all discussions about probability. Before you can define probability in statistical terms, you need to understand the meaning of an event**.**

#### Event

**CONCEPT** An outcome of an experiment or survey.

**EXAMPLES** Rolling a die and ...