CHAPTER 16 Getting Straight Talk on Straight-Line Regression 213

Chapter 16

Getting Straight Talk on

Straight-Line Regression

C

hapter  15 refers to regression analyses in a general way. This chapter

focuses on the simplest type of regression analysis: straight-line regression.

You can visualize it as fitting a straight line to the points in a scatter plot

from a set of data involving just two variables. Those two variables are generally

referred to as X and Y. The X variable is formally called the independent variable (or

the predictor or cause). The Y variable is called the dependent variable (or the out-

come or effect).

Knowing When to Use Straight-Line

Regression

You may see straight-line regression referred to in books and articles by several

different names, including linear regression, simple linear regression, linear univariate

regression, and linear bivariate regression. This abundance of references can be con-

fusing, so we always use the term straight-line regression.

IN THIS CHAPTER»

» ^{Determining when to use straight-}

line regression»

» ^{Running a straight-line regression}

and making sense of the output»

» ^{Examining results for issues and}

problems»

» ^{Estimating needed sample size for}

straight-line regression