# Social Statistics for a Diverse Society

# Chapter Summary

**Chapter 13**

A scatter diagram (also called scatterplot) is a quick visual method used to display relationships between two interval-ratio variables.

Equations for all straight lines have the same general form:

Y^ = *a *+ *b*(*X*)

The best-fitting regression line is that line where the residual sum of squares, or Σ*e*2, is at a minimum. Such a line is called the least squares line, and the technique that produces this line is called the least squares method.

The coefficient of determination (*r*2) and Pearson’s correlation coefficient (*r*) measure how well the regression model fits the data. Pearson’s *r *also measures the strength of the association between the two variables.

The general form of the multiple regression equation involving two independent variables is*Y*^ = *a *+ *b*1(*X*1) + *b*2(*X*2)