35.1 Introduction

In the last chapter, correlation was studied, which measures the strength of the linear relationship between two quantitative variables $x$ and $y$. We now study regression, which describes what the linear relationship is between $x$ and $y$.

The relationship is described using an equation, which allows us to:

1. Predict values of $y$ from given values of $x$ (Sect. 35.4); and
2. Understand the relationship between $x$ and $y$ (Sect. 35.5).