Probability is an important and complex field
of study. Fortunately, only a few basic issues
in probability theory are essential for understanding statistics
at the level covered in this book. These basic issues are covered
in this chapter.

The introductory
section discusses the definitions
of probability. This is not as simple as it may seem. The section
on basic concepts covers how to compute
probabilities in a variety of simple situations. The Gambler's
Fallacy Simulation provides an opportunity to explore this
fallacy by simulation. The Birthday Demonstration illustrates
the probability of finding two or more people with the same birthday.
The Binomial Demonstration shows the binomial distribution for
different parameters. The section on base rates discusses
an important but often-ignored factor in determining probabilities.
It also presents Bays' Theorem. The Bays' Theorem Demonstration
shows how a tree diagram and Bays' Theorem result in the same
answer. Finally, the Monty Hall Demonstration lets you play a
game with a very counterintuitive result.