PO218 Lecture Notes - Lecture 13: Scatter Plot, Display Device, Dependent And Independent Variables
Document Summary
Chapter 13: association between variables measured at the interval ratio level. Scattergram: a graphic display device that depicts the relationship between two variables. They provide at least impressionistic information about the existence, strength, and direction of the relationship and can also be used to check the relationship for linearity. If these two variables had not been associated, the conditional distributions of y would not have changed, and the regression line would have been parallel to the horizontal axis. The strength of the bivariate association can be judged by observing the spread of the dots around the regression line. In a perfect association, all dots would lie on the regression line. The more the dots are clustered around the regression line, the stronger the association. Regression and prediction: a final use of the scattergram is to predict scores of cases on one variable from their score on the other.
