J :9. The regression line for a scatter diagram is an approximation of its graph of averages. For some scatter diagrams, all of the points of the graph of averages lie on a straight line. This straight line is then the regression line. For other scatter diagrams, the points of the graph of averages do not all lie on a straight line, and so, of course, they do not all lie on the regression line. + Now consider the six scatter +J diagrams of diagram ? on page ?? of the test. The points of the graph of averages all lie on the regression line of
e. four or five
of the six scatter diagrams.