Regression involves specifying the relationship between a single numeric **dependent variable** (the value to be predicted) and one or more numeric **independent variables** (the predictors). As the name implies, the dependent variable depends upon the value of the independent variable or variables. The simplest forms of regression assume that the relationship between the independent and dependent variables follows a straight line.

### Note

The origin of the term "regression" to describe the process of fitting lines to data is rooted in a study of genetics by Sir Francis Galton in the late 19th century. He discovered that fathers who were extremely short or tall tended to have sons whose heights were closer to the average height. He called this phenomenon "regression to the mean."

You might recall from basic algebra that lines can be defined in a **slope-intercept form** similar to *y = a + bx*. In this form, the letter *y* indicates the dependent variable and *x* indicates the independent...