| one of a number of measures of correlation, usually assuming values from +1 to −1. |
| correlation coefficient n. A measure of the interdependence of two random variables that ranges in value from -1 to +1, indicating perfect negative correlation at -1, absence of correlation at zero, and perfect positive correlation at +1. Also called coefficient of correlation. |
Correlation Coefficient
A measure that determines the degree to which two variable's movements are associated.
The correlation coefficient is calculated as: 
Investopedia Commentary
The correlation coefficient will vary from -1.0 to 1.0. -1.0 indicates perfect negative correlation, and 1.0 indicates perfect positive correlation.
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See also: Coefficient of Variation, Correlation, Covariance
