The standard error of the residual in the regression equation (2.17) also has a useful interpretation. Specifically, while the left-hand side of Eq, (2.17) reflects the effects of both specific(unsystematic) and market (systematic)risk on the portfolio in company J. the Beta(rm-rf) term on the right-hand side reflects only the impact of market risk. It therefore follows that the estimated, residual in Sq. (2.17) incorporates only the effects of specific (unsystematic) risk. The standard error of the residual (also often called the standard error of the regression), computed as the square root of S2, defined as