1 - correlation between 2 quantitative variables (r)

The Pearson correlation coefficient, commonly denoted as r, is a measure of the linear relationship between two quantitative variables. It ranges between -1 and 1, where -1 indicates a perfect negative linear correlation, 0 indicates no correlation, and 1 indicates a perfect positive linear correlation. It evaluates the extent to which changes in one variable can be predicted from changes in the other.