4.4 The Exponential and Gamma Distributions

Content

• 4.4.1 The Exponential Distribution
• 4.4.2 The Gamma Function
• 4.4.3 The Gamma Distribution
• 4.4.4 The Chi-Squared Distribution
• EXERCISES Section 4.4 (59-71)

Introduction

The density curve corresponding to any normal distribution is bell-shaped and therefore symmetric. There are many practical situations in which the variable of interest to an investigator might have a skewed distribution. One family of distributions that has this property is the gamma family. We first consider a special case, the exponential distribution, and then generalize later in the section.