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Pearson’s correlation coefficient, a measurement quantifying the strength of the association between two variables. Pearson’s correlation coefficient r takes on the values of −1 through +1. Values of −1 or +1 indicate a perfect linear relationship between the two variables, whereas a value of 0 indicates no linear relationship. (Negative values simply indicate the direction of the association, whereby as one variable increases, the other decreases.) Correlation coefficients that differ from 0 but are not...