1. Does it matter which axis is used for a particular set of data on a scatter diagram?
Not usually. Any connection will be apparent whichever set of data is plotted on a particular axis.
2. What does r stand for in the study of regression and correlation?
r stands for the correlation coefficient. The nearer the value of r is to 1 or -1, the closer the points on a scatter diagram are to fitting a straight line.
