巴罗宏观经济学现代观点8章课件.pptx

1、Macroeconomics Chapter 8 1Cyclical Behavior of Real GDPRecessions and Booms Real GDP =trend real GDP+cyclical part of real GDP Cyclical part of real GDP Coming from the business cycle Short-term economic fluctuations.Macroeconomics Chapter 8 2Cyclical Behavior of Real GDPRecessions and BoomsMacroeco

2、nomics Chapter 8 3Cyclical Behavior of Real GDPRecessions and BoomsMacroeconomics Chapter 8 4Cyclical Behavior of Real GDPRecessions and BoomsMacroeconomics Chapter 8 5An Equilibrium Business-Cycle ModelMacroeconomics Chapter 8 6An Equilibrium Business-Cycle Model Conceptual Issues Assuming that the

3、se fluctuations reflect shocks to the economy.Change in level of technology Y=A F(K,L)An increase in A means that the economy is more productive.A decrease in A means that the economy is less productive.Macroeconomics Chapter 8 7An Equilibrium Business-Cycle Model Uses equilibrium conditions to dete

4、rmine how the shocks affect real GDP,Y,and other macroeconomic variables,such as consumption,C,investment,I,and the quantity of labor input,L.RBC model Finn Kydland&Edward Prescott（2004 Nobel Laureates）Macroeconomics Chapter 8 8An Equilibrium Business-Cycle Model The Model Y=A F(K,L)the capital stoc

5、k,K,as fixed in the short run,the labor input,L,is fixed.Changes in Y will reflect only changes in A.When A rises,Y rises,When A falls,Y falls.Macroeconomics Chapter 8 9An Equilibrium Business-Cycle Model The Model The marginal product of labor and the real wage rate An increase in the technology le

6、vel,A,raises the marginal product of labor,MPL,for given inputs of capital,K,and labor,L.Macroeconomics Chapter 8 10An Equilibrium Business-Cycle ModelMacroeconomics Chapter 8 11An Equilibrium Business-Cycle ModelMacroeconomics Chapter 8 12An Equilibrium Business-Cycle Model The Model Marginal produ

7、ct of capital,real rental price,and the interest rate An increase in the technology level,A,raises the marginal product of capital,MPK,for given inputs of capital,K,and labor,LMacroeconomics Chapter 8 13An Equilibrium Business-Cycle ModelMacroeconomics Chapter 8 14An Equilibrium Business-Cycle Model

8、Macroeconomics Chapter 8 15An Equilibrium Business-Cycle Model Marginal product of capital,real rental price,and the interest rate i=R/P i=MPK(evaluated at given K and L)The model predicts that an economic boom will have a relatively high interest rate,whereas a recession will have a relatively low

9、interest rate.Macroeconomics Chapter 8 16An Equilibrium Business-Cycle Model Consumption,saving,and investment Aggregate household budget constraint Given the markets for bonds,labor,and capital services clear:C+K=Y KMacroeconomics Chapter 8 17An Equilibrium Business-Cycle Model C+K=A F(K,L)K deprec

10、iation,K,is fixed in the short run,An increase in A raises real GDP for given K and L,we see that a rise in A raises overall real income.Macroeconomics Chapter 8 18An Equilibrium Business-Cycle Model Consumption,saving,and investment income effect：The increase in real income motivates households to

11、raise current consumption and future consumption.Intertemporal-substitution effect：The increase in the interest rate tends to reduce current consumption.The net change depends on whether the income effect is stronger or weaker than the intertemporal-substitution effect.Macroeconomics Chapter 8 19An

12、Equilibrium Business-Cycle Model Consumption,saving,and investment Assume that the change in A is permanent.the increases in real income tend also to be permanent.The propensity to consume out of higher income would be close to one.When the increase in A is permanent,current consumption will rise.Ho

13、wever,as long as the intertemporal-substitution operates at all,the increase in current consumption will be less than the increase in real GDP.Macroeconomics Chapter 8 20An Equilibrium Business-Cycle Model Consumption,saving,and investment Since current consumption,C,rises,but by less than the incre

14、ase in real GDP,Y.Therefore,net investment,K,must increase-the increase in real GDP shows up partly as more C and partly as more K.Since net investment,K,equals real saving,this result is consistent with our finding that real saving increased.Macroeconomics Chapter 8 21Matching the Theory with the F

15、acts Consumption and Investment When a variable fluctuates in the same direction as real GDP that variable is procyclical.A procyclical variable moves in the same direction as the business cycleit tends to be high relative to its trend in a boom and low relative to its trend in a recession.Macroecon

16、omics Chapter 8 22Matching the Theory with the Facts Consumption and Investment A variable that fluctuates in the opposite direction from real GDP is countercyclical.One that has little tendency to move in a particular direction during a business cycle is acyclical.Macroeconomics Chapter 8 23Matchin

17、g the Theory with the FactsMacroeconomics Chapter 8 24Matching the Theory with the FactsMacroeconomics Chapter 8 25Matching the Theory with the Facts Consumption and Investment Permanent shifts in the technology level,A,match up with some of the empirical patterns Increases in A generate economic bo

18、oms,where real GDP increases,consumption and investment increases.Decreases in A create recessions,where real GDP,consumption,and investment all decline.Macroeconomics Chapter 8 26Matching the Theory with the Facts The Real Wage Rate The model predicts that the real wage rate,w/P,will be relatively

19、high in booms and relatively low in recessions.Macroeconomics Chapter 8 27Matching the Theory with the FactsMacroeconomics Chapter 8 28Matching the Theory with the Facts The Real Rental Price The model predicts that the real rental price of capital,R/P,will be relatively high in booms and relatively

20、 low in recessions.Macroeconomics Chapter 8 29Matching the Theory with the FactsMacroeconomics Chapter 8 30Matching the Theory with the Facts The Interest Rate The model predicts that booms will have a high interest rate,i,whereas recessions will have a low interest rate.Macroeconomics Chapter 8 31T

21、emporary Changes in the Technology Level A decrease in A due to a harvest failure or a general strike would be temporary.To allow for these cases,we now assume that the change in A is temporary.Macroeconomics Chapter 8 32Temporary Changes in the Technology Level If A increases temporarily,real GDP,A

22、 F(K,L),still rises for fixed values of K and L.The marginal product of capital,MPK,and the interest rate,i,also rise as before.The intertemporal-substitution effect from the higher i still motivates households to reduce current consumption,C,and raise current real saving.Macroeconomics Chapter 8 33

23、Temporary Changes in the Technology Level The model therefore predicts that economic boom would feature high real GDP and investment.Consumption would rise by a small amount.A recession would have low real GDP and investment.Consumption would decline by a modest amount.Macroeconomics Chapter 8 34Var

24、iations in Labor Input Labor Supply More labor supplied means less leisure time for the family.Assume that households also like more leisure time.As with consumption and saving,the choice of Ls involves substitution and income effects.Macroeconomics Chapter 8 35Variations in Labor Input The substitu

25、tion effect for leisure and consumption If the household chooses to work one more hour and thereby have one less hour of leisure,the extra w/P of real wage income pays for w/P more units of consumption.Therefore,the household can substitute one less hour of leisure for w/P more units of consumption.

26、Macroeconomics Chapter 8 36Variations in Labor Input The substitution effect for leisure and consumption If w/P rises,the household gets a better deal by working more because it gets more consumption for each extra hour worked.Since the deal is better,we predict that the household responds to a high

27、er w/P by working more.Macroeconomics Chapter 8 37Variations in Labor Input The substitution effect for leisure and consumption A higher real wage rate,w/P,raises the quantity of labor supplied,LsMacroeconomics Chapter 8 38Variations in Labor Input Income effects on labor supply A higher w/P means h

28、igher real wage income,(w/P)Ls Household spends the extra income on consumption and leisure time.A higher w/P leads to a smaller quantity of labor supplied,Ls.Macroeconomics Chapter 8 39Variations in Labor Input Income effects on labor supply Resolve the ambiguity by considering whether the income e

29、ffect is strong or weak C1+C2/(1+i1)+C3/(1+i1)(1+i2)+=(1+i0)(B0/P+K0)+(w/P)1Ls1+(w/P)2Ls2/(1+i1)+(w/P)3Ls3/(1+i1)(1+i2)+Macroeconomics Chapter 8 40Variations in Labor Input Income effects on labor supply A permanent increase in real wage rates results in a large income effect.If the change in year 1

30、s real wage rate,(w/P)1,is temporary,the income effect is small.The income effect will be weaker than the substitution effect.Macroeconomics Chapter 8 41Variations in Labor Input Intertemporal-substitution effects on labor supply C1+C2/(1+i1)+C3/(1+i1)(1+i2)+=(1+i0)(B0/P+K0)+(w/P)1Ls1+(w/P)2Ls2/(1+i

31、1)+(w/P)3Ls3/(1+i1)(1+i2)+Macroeconomics Chapter 8 42Variations in Labor Input Intertemporal-substitution effects on labor supply.If the interest rate,i1,rises,a unit of year2s real wage income,(w/P)2Ls2,becomes less valuable as a present value compared to a unit of year1s real wage income,(w/P)1Ls

32、1.We therefore predict that the household would increase Ls1 and decrease Ls2 as the interest rate increases.Macroeconomics Chapter 8 43Variations in Labor InputMacroeconomics Chapter 8 44Variations in Labor Input Fluctuations in Labor Input Measures of labor input are procyclical:they move in the s

33、ame direction as real GDP during booms and recessions.Employment Total hours workedMacroeconomics Chapter 8 45Variations in Labor InputMacroeconomics Chapter 8 46Variations in Labor Input The cyclical behavior of labor input:theory Increase in A will lead to:The real wage rate increases Labor inputs

34、 increase.Macroeconomics Chapter 8 47Variations in Labor InputMacroeconomics Chapter 8 48Variations in Labor Input The cyclical behavior of labor productivity Measures of labor productivity,Y/L,is real GDP per worker,Real GDP per worker-hour.Labor productivity turns out to be procyclical in both cas

35、es.Macroeconomics Chapter 8 49Extra：labor supply modelFor simplicity:the household has only one member and he lives only for one period and has no initial wealth.FOC:ttttttllwctsblbcut.01lnlnmax,ctcwllbcL1lnln01c01wlb Macroeconomics Chapter 8 50Extra：labor supply modelIntuition:In one period,the inc

36、ome and substitution effects of a change in the wage offset each other.bl11*Macroeconomics Chapter 8 51Extra：labor supply model 212211221111111lnln111lnlncrclwrlwlbclbcL01)1(10121rcc011)1)(1(012211wrlbwlbTwo periods:FOC:Macroeconomics Chapter 8 52Extra：labor supply model 1221211111,11wwrllrcc Intuition:intertemporal substitution in labor supply