The correlation does not change when the units of measurement of either one of the variables change. In other words, if we change the units of measurement of the explanatory variable and/or the response variable, this has no effect on the correlation (r).

Does correlation have units of measurement?

The correlation coefficient r is a unit-free value between -1 and 1. Statistical significance is indicated with a p-value. Therefore, correlations are typically written with two key numbers: r = and p = .

What changes the correlation?

Adding, subtracting, multiplying or dividing a constant to all of the numbers in one or both variables does not change the correlation coefficient. This is because the correlation coefficient is, in effect, the relationship between the z-scores of the two distributions.