Using the Taylor expansion for approximating around the steady state, MRW derive a regression equation to estimate the speed of convergence conditional on what they hold to be the ืdeterminant(s) of the steady state, namely the capital–output ratio(s). Again abstracting from all detail, starting from equation (4), and using the same derivation as MRW, one would end up with an equation that describes the growth of output per working-age person as a function of the capital–output ratio and the initial level of income.10 But as before, one could argue that the variation in technology rather than the variation in the capital–output ratio should be the conditional factor for the steady state, so a measure of a broad concept of technology should be included in the regression equation that is used to estimate the speed of convergence. In the simplest case with two factors of production, such an equation would read