The calculation of a standard deviation involves taking the positive square root of a nonnegative number. As a result, both standard deviations in the formula for the slope must be nonnegative. ... Therefore the sign of the correlation coefficient will be the same as the sign of the slope of the regression line.
The calculation of a standard deviation involves taking the positive square root of a nonnegative number. As a result, both standard deviations in the formula for the slope must be nonnegative. ... Therefore the sign of the correlation coefficient will be the same as the sign of the slope of the regression line.
