Correlation coefficient ‘r’

A bivariate descriptive statistic, appropriate in dealing with two intervally-scaled variables, which provides a measure of the linear direction and strength of the relationship between these variables. It is also sometimes known as product moment correlation. Karl Pearson originally proposed it, therefore it is also known as Pearson’s correlation coefficient. In fact it goes by different names such as simple correlation, bivariate correlation or product moment correlation or merely the correlation coefficient.