Definition: A measure of association is a statistical quantity used to indicate the strength of the relationship between two variables. Measures of association take on values ranging from -1.0 to +1.0, with the positive and negative signs indicating the direction of the relationship, not the strength of the relationship.
Examples:-0.45 and +0.45 indicate equally strong relationships, only one is a negative relationship and one is a positive relationship. A value of 1.0 (regardless of sign) indicates a perfect relationship in which variable X allows us to predict the score on variable Y without making any errors. A score of 0.00 means the two variables are independent of each other and not related at all.