regardless of the initial conditions. [8 p. 261] This means that the difference between the equilibrium value and the actual value of x is bounded for a large enough t, and that this difference tends to zero as t becomes large. So, it has been attractive to assume a monotonic convergence and to approximate the process of adjustment (or convergence) by an adjustment equation such as that used implicitly by Koyck [3] and explicitly by Nerlove [6, 7]