Chapter 9
The t-Distribution
IN THIS CHAPTER
Characteristics of the t-distribution
Relationship between Z- and t-distributions
Understanding the t-table
Many different distributions exist in statistics, and one of the most commonly used distributions is the t-distribution. In this chapter, I go over the basic characteristics of the t-distribution, how to use the t-table to find probabilities, and how it’s used to solve problems in its most well-known settings — confidence intervals and hypothesis tests.
Basics of the t-Distribution
The normal distribution is the well-known bell-shaped distribution whose mean is
and whose standard deviation is
. (See Chapter 5 for more on normal distributions.) The t-distribution can be thought of as a cousin of the normal distribution — it looks similar to a normal distribution in that it has a basic bell shape with an area of 1 under it, but is shorter and flatter than a normal distribution. Like the standard normal (Z) distribution, it is centered ...