宏观经济学曼昆七1-9chapter 8

1、CHAPTER 8Economic Growth II: Technology, Empirics and PolicyA PowerPointTutorialTo AccompanyMACROECONOMICS, 7th. EditionN. Gregory MankiwTutorial written by:Mannig J. SimidianB.A. in Economics with Distinction, Duke UniversityChapter Eight1M.P.A., Harvard University Kennedy School of GovernmentM.B.A

2、., Massachusetts Institute of Technology (MIT) Sloan School of ManagementChapter Eight2The Solow model does not explain technological progress but, instead, takes it as given and shows how it interacts with other variables in the process of economic growth.To examine how a nations public policies ca

3、n influence the level and growth of the citizens standard of living, we must ask five questions.1)2)3)4)Should our society save more or less?How can policy influence the rate of saving?Are there some types of investment that policy should encourage? What institutions ensure that the economys resourc

4、es are putto their best use?5)How can policy increase the rate of technological progress?The Solow model provides the theoretical framework within which we consider these issues.Chapter Eight3To incorporate technological progress, the Production Function is now written as:Y = F (K, L E)The term L E

5、measures the number of workers.This takes into account the number of workers L and the efficiency of each worker, E.It states that total output Y depends on capital K and workers L E. The essence of this model is that increases in E (efficiency) are analogous to increases in L (number of workers). I

6、n other words, a single worker (if twice as productive)can be thought of as two workers. L E doubles and the economybenefits from the increased production of goods and services.Chapter Eight4Technological progress causes E to grow at the rate g, and L grows at rate n so the number of workers L E is

7、growing at rate n + g.Now, the change in the capital stock per worker is:Dk = i (d+n +g)k, where i is equal to s f(k).sf(k)(d + n + g)kThe Steady StateNote: k = K/LE and y=Y/(L E).So, y = f(k) is now different.Also, when the g term is added, gk is needed to provided capital to new “effective workers

8、” created by technological progress.Investment,sf(k)k*Capitalper worker, kChapter Eight5Labor-augmenting technological progress at rate g affects the Solow growth model in much the same way as did population growth at raten. Now that k is defined as the amount of capital per effective worker, increa

9、ses in the number of effective workers because of technological progress tend to decrease k.In the steady state, investment sf(k) exactly offsets the reductions in k because of depreciation, population growth, and technological progress.Chapter Eight6ImportantChapter Eight7Capital per effective work

10、er is constant in the steady state. Because y = f(k), output per effective worker is also constant. But the efficiency of each actual worker is growing at rate g. So, output per worker, (Y/L = y E) also grows at rate g. Total output Y = y (E L) grows at rate n + g.The introduction of technological p

11、rogress also modifies the criterion for the Golden Rule.The Golden Rule level of capital is now defined as the steady state that maximizes consumption per effective worker. So, we can show that steady-state consumptionper effective worker is:c*= f (k*) - (d + n + g) k*Steady-state consumption is max

12、imized ifMPK = d + n + g,rearranging, MPK - d = n + g.That is, at the Golden Rule level of capital, the net marginal product of capital, MPK - d, equals the rate of growth of totaloutput, n + g.Because actual economies experience bothpopulation growth and technological progress, we must use this cri

13、terion to evaluate whether they have more or less capital than they would at the Golden Rule steady state.Chapter Eight8k = K/(E L)y = Y/ (E L) = f(k) Y/L = y EY = y (E L)Capital per effective worker Output per effective worker Output per workerTotal output00gn + gChapter Eight9So far we have introd

14、uced technological progress into the Solow model to explain sustained growth in standards of living. Lets now discuss what happens when theory meets facts.Chapter Eight10According to the Solow model, technological progress causes the values of many variables to rise together in the steady state This

15、 property is called balanced growth.In the steady state, output per worker, Y/L, and capital stock per worker, K/L, both grow at rate g, which is the rate of technological progress. This is consistent with U.S. data in that g has beenabout 2 percent consistently over the past 50 years.Technological

16、progress also affects factor prices. The real wage grows at the rate of technological progress, but the real rental price of capital remains constant over time. Again, over the last50 years, the real wage has increased by 2 percent and has increased by about the same as real GDP. Yet, the real renta

17、l price of capital (real capital income divided by the capital stock) has been about the same.Chapter Eight11The property of catch-up is called convergence. If there is not convergence, countries that start off poor are likely to remain poor.The Solow model makes predictions about when convergence s

18、hould occur. According to the model, whether two economies will converge depends on why they differ in the first place (i.e., savings rates,population growth rates, and human capital accumulation).Chapter Eight12Differences in income are a result of either:1) Factors of production such as the quanti

19、ties of physical and human capital2) Efficiency with which economies use their factors of productionPut simply, workers in a poor country either dont have the toolsand skills, or they are not putting their tools and skills to the best use.Chapter Eight13Chapter Eight14In terms of the Solow model, th

20、e central question is whether the large gap between the rich and poor is explained by differences in capital accumulation, or differences in the production function.The savings rate determines the steady-state levels of capital and output. One particular saving rate produces the Golden Rule steady s

21、tate, which maximizes consumption per worker. Lets use the Golden Rule to analyze the U.S. saving rate.Chapter Eight15Recall that at the Golden Rule steady state, (MPK d) = (n + g)Growth rate of total output(n + g)Marginal product of capital net of depreciation(MPK d)Amount of capital in the Golden

22、Rule steady stateChapter Eight16If the economy is operating with less capital than in the Golden Rule steady state, then (MPK d n + g)If the economy is operating with more capital than in the Golden Rule steady state, then (MPK d revenue, it is a budget deficit LWhen spending d, the economys income grows forever, even without the assumption of exogenous technol