Several other econometric issues should briefly noted. The printed output of computer regression programs typically includes measures of R2, the standard error of the regression, and z-statistics. These and other standard statistical measures have a particularly interesting interpretation and application within the CAPM. Consider, for example, the simple correlation between the risk premium on the security j (Rj -Rf) and the market risk premium (rm - rf)-variables that are on the left- and right-hand sides, respectively, of the CAPM regression equation (2.17). The sample correlation coefficient between them can be rewritten as follows