新古典经济增长理论讲解.ppt

* Of course, “actual investment” and “break-even investment” here are in “per worker” magnitudes. * * * This and the preceding slide establish an implication of the model. Let’s next see whether it is consistent with the data. * Figure 7-13 on p. 203. The model predicts that faster population growth should be associated with a lower long-run income per capital The data is consistent with this prediction. So far, we’ve now learned two things a poor country can do to raise its standard of living: increase national saving (perhaps by reducing its budget deficit) and reduce population growth). * * * * * * The only thing that’s new here is that gk is part of break-even investment. Remember: k = K/LE, capital per effective worker. Tech progress increases the number of effective workers at rate g, which would cause capital per effective worker to fall at rate g (other things equal). Investment equal to gk would prevent this. * The equation that appears above the graph is the equation of motion modified to allow for technological progress. There are minor differences between this and the Solow model graph from Chapter 7: Here, k and y are in “per effective worker” units rather than “per worker” units. The break-even investment line is a little bit steeper: at any given value of k, more investment is needed to keep k from falling--in particular, gk is needed. Otherwise, technological progress will cause k = K/LE to fall at rate g (because E in the denominator is growing at rate g). With this graph, we can do the same policy experiments as in Chapter 7. We can examine the effects of a change in the savings or population growth rates, and the analysis would be much the same. The main difference is that in the steady state, income per worker/capita is growing at rate g instead of being constant. * 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