Correlation coefficient

Abstract

Correlation coefficient (r) is an index of association between continuous variables. The coefficient • r ' may have values ranging from + 1 to — 1. r = +1 corresponds to a rectilinear relationship (of the form y=a+bx) in which the two variables are positively related. r=—1 corresponds to a rectilinear relationship (of the form y=a-bx) in which the two variables are negatively related. Values of' r ' near -f 1 (or—1) indicate an approach to a rectilinear relationship. But intermediate values of ' r ' are more difficult to interpret (Parker, 1973). Values of ' r ' near zero may arise under two conditions : 1. when there is no relationship and 2. when there is a real relationship but it is curvi-linear.