Describing the Relationship between Two Quantitative Variables: Regression
In the Chapter 6, we introduced situations in which there are two or more variables measured on each case, such as height and weight measures for athletes, and moved from descriptions of univariate distributions to descriptions of bivariate distributions. In considering the possibility that two variables might “move together,” or correlate, we assumed that the relationships being described were linear. We traced the development of a measure of the strength of the linear relationship, or the degree to which the data points in the scatterplot appeared to fall on a line. In particular, we showed you how to calculate the Pearson Product-Moment Correlation coefficient. We also described other ways to measure the strength of the relationship between two variables. In this chapter, we will describe the process of regression, or how one variable changes as a function of the other.