### Background: Predicting a Criterion Variable from Multiple Predictors

The criterion (or predicted) variable in multiple regression is represented by the symbol Y, and is therefore often referred to as the “Y variable.” The predictor variables are represented as X_{1}, X_{2}, X_{3}... X_{n}, and are referred to as the “X variables” (i.e., independent variables). The purpose of multiple regression is to understand the relationship between the Y variable and the X variables when taken as a group.

#### A Simple Predictive Equation

For example, consider again the model of the determinants of prosocial behavior presented in Figure 14.1. This model hypothesizes that the number of prosocial acts performed by an individual in a given period of time can be predicted by ...