This document discusses covariance and the Pearson r correlation coefficient. Covariance measures the relationship between two variables, indicating whether it is positive or negative. Pearson r standardizes the covariance to produce a value between -1 and 1 that represents how well one variable can predict the other. It answers whether a relationship exists, its direction, and strength. A value of 0 means no relationship; higher positive or negative values indicate a stronger linear relationship. Pearson r cannot be compared between studies and the covariance determines its sign.