曼昆经济学原理(宏观经济分册)3.ppt

* Next, we see what the model says about the relationship between a country’s saving rate and its standard of living (income per capita) in the long run (or steady state). An earlier slide said that the model’s omission of G and T was only to simplify the presentation. We can still do policy analysis. We know from Chapter 3 that changes in G and/or T affect national saving. In the Solow model as presented here, we can simply change the exogenous saving rate to analyze the impact of fiscal policy changes. * Graph to be updated for final version of this PowerPoint presentation. * Of course, “actual investment” and “break-even investment” here are in “per worker” magnitudes. * * * Of course, the converse is true, as well: a fall in s (caused, for example, by tax cuts or government spending increases) leads ultimately to a lower standard of living. In the static model of Chapter 3, we learned that a fiscal expansion crowds out investment. The Solow model allows us to see the long-run dynamic effects: the fiscal expansion, by reducing the saving rate, reduces investment. If we were initially in a steady state (in which investment just covers depreciation), then the fall in investment will cause capital per worker, labor productivity, and income per capita to fall toward a new, lower steady state. (If we were initially below a steady state, then the fiscal expansion causes capital per worker and productivity to grow more slowly, and reduces their steady-state values.) * * * Explanations: k is constant (has zero growth rate) by definition of the steady state y is constant because y = f(k) and k is constant To see why Y/L grows at rate g, note that the definition of y implies (Y/L) = yE. The growth rate of (Y/L) equals the growth rate of y plus that of E. In the steady state, y is constant while E grows at rate g. Y grows at rate g + n. To see this, note that Y = yEL = (yE)?L. The growth rate of Y equals the growth rate of (yE) plus that of L.