Correlation coefficients are used to measure the strength of the relationship between two variables.
The Pearson correlation is most commonly used in statistics. It measures the strength and direction of a linear relationship between two variables.
Values are always between -1 (strong negative association) and +1 (strong positive association). Values equal to or close to zero imply little or no linearity.
Correlation coefficient values less than +0.8 or greater than -0.8 are not considered significant.