Number between −1 and +1 which measures the degree to which two variables are linearly related. −1 indicates perfect linear negative relationship between two variables, +1 indicates perfect positive linear relationship and 0 indicates lack of any linear relationship.
A number, referred to as r, that expresses both the size and the direction of a correlation q.v., varying from +1.00 through 0.00 to — 1.00. Plus 1.00 is perfect, positive correlation, 0.00 is no correlation, while —1.00 is perfect negative correlation.