Statistical measure of the linear relationship or correlation between an independent variable and a dependent variable. Represented by the lowercase letter ‘r’, its value of worth varies between 1 and 0, where 1 means perfect correlation, 0 means no correlation. Positive worths means the relationship is positive – when one goes up so does the other. Negative worths mean the relationship is negative – when one goes up the other goes down. Known also as correlation coefficient. Refer also to correlation.