The symbol r², often referred to as R-squared, represents the coefficient of determination in statistics. It’s primarily used in the context of regression analysis to measure the proportion of the variance in the dependent variable that can be explained by the independent variables.
However, in the realm of correlation coefficients, it can also refer to the square of the Pearson correlation coefficient (r), which measures the strength and direction of a linear relationship between two continuous variables. In this case, the value of r² ranges from 0 to 1, where 0 indicates no correlation and 1 indicates a perfect positive correlation.
It’s important not to confuse r² with Spearman’s rank correlation coefficient, which is another statistical measure used for assessing how well the relationship between two variables can be described by a monotonic function. Additionally, r² is not used for sample standard deviation, population, or median of sets.