Final answer:
Spearman's rho describes the strength and direction of a monotonic relationship between two ranked variables, differing from Pearson's r which measures linear relationships.
Step-by-step explanation:
Spearman's rho is a statistical measure that describes the strength and direction of the association between two ranked variables. It is a nonparametric measure of rank correlation, meaning it assesses how well the relationship between two variables can be described using a monotonic function.
While the Pearson correlation coefficient, denoted as r, measures the strength of the linear relationship between two quantitative variables, Spearman's rho is more versatile as it can handle non-linear relationships provided that they are monotonic. Similar to Pearson's r, Spearman's rho ranges from -1 to +1. A value of +1 indicates a perfect increasing monotonic relationship, while a value of -1 indicates a perfect decreasing monotonic relationship. A value of 0 would indicate no correlation.