COVARIANCE

(Statistics) A measure of the linear association between two variables. If both variables are always above and below their means at the same time, the covariance is said to be positive. If one variable is above its mean when the other variable is below its mean and vice versa, the covariance is said to be negative. The value of the covariance is dependent upon the units in which each variable is measured whereas the Correlation Coefficient is a measure of this association which has been normalized and is therefore "unit free."