专业课资料 练习题 真题 曼昆宏观英文版讲义 Ecn101_lecture4

1 macroeconomics fifth edition N Gregory Mankiw PowerPoint Slides by Ron Cronovich macro 2003 Worth Publishers all rights reserved CHAPTER THREE National Income Where it Comes From and Where it Goes 1 Econ 101 Intermediate Macro Theory Lecture notes Professor Cetorelli UC Davis Fall 2003 Lecture 4 2 Reading so far Chapter 1 pp 1 14 Chapter 2 pp 15 23 bottom section excluded 24 27 bottom section excluded 30 38 Chapter 3 pp 42 69 Exclude FYI boxes p 57 66 2 3 Reading for next lecture Finish reading Chapter 3 Appendix to Chapter 3 pp 71 73 Jump to Chapter 7 pp 180 195 4 Summary from last time 5 Summary continued We looked at first economic model for the determination of aggregate output Made important assumption 1 Closed economy no international trade 2 Two factors of production K and L 3 Production function Y F K L isCRS Initially Y1 F K1 L1 Scale all inputs by the same factor z K2 zK1 and L2 zL1 If Y2 F K2 L2 zY1 then constant returns to scale 3 6 Additional assumptions of the model 4 Technology is fixed 5 The economy s supplies of capital and labor are fixed at and KKLL Hence total aggregate output is exogenously determined by the given state of the technology and by the given units of capital and labor available for production YF K L 7 Summary continued How is income distributed It depends on the price paid to hire the owners of the factors of production K and L Recall from Chapter 2 the value of output equals the value of income The income is paid to the workers and capital owners 8 Notation W nominal wage R nominal rental rate P price of output W P real wage measured in units of output R P real rental rate W nominal wage R nominal rental rate P price of output W P real wage measured in units of output R P real rental rate 4 9 Summary continued 6 Additional assumption The markets for capital and labor are perfectly competitive prices are taken as given 7 Production function characterized by diminishing marginal productivity of K and L Firms hire K and L up to the point where the cost of hiring one additional unit does not exceed the marginal increase in production that the additional factor unit is able to contribute CHAPTER 3CHAPTER 3National IncomeNational Income slide 10 Marginal product of labor Marginal product of labor MPLMPL def The extra output the firm can produce using an additional unit of labor holding other inputs fixed MPL F K L 1 F K L CHAPTER 3CHAPTER 3National IncomeNational Income slide 11 answers answers Production function 0 10 20 30 40 50 60 0123456789 10 Labor L Output Y Marginal Product of Labor 0 2 4 6 8 10 12 0123456789 10 Labor L MPL units of output 5 CHAPTER 3CHAPTER 3National IncomeNational Income slide 12 MPLMPL and the demand for laborand the demand for labor Each firm hires labor up to the point where MPL W P Each firm hires labor up to the point where MPL W P Units of output Units of labor L MPL Labor demand Real wage Quantity of labor demanded CHAPTER 3CHAPTER 3National IncomeNational Income slide 13 End of summaryEnd of summary CHAPTER 3CHAPTER 3National IncomeNational Income slide 14 The equilibrium real wageThe equilibrium real wage The real wage adjusts to equate labor demand with supply The real wage adjusts to equate labor demand with supply Units of output Units of labor L MPL Labor demand equilibrium equilibrium real wagereal wage Labor supply L 6 CHAPTER 3CHAPTER 3National IncomeNational Income slide 15 Determining the rental rateDetermining the rental rate In our model it s easiest to think of firms renting capital from households the owners of all factors of production R P is the real cost of renting a unit of K for one period of time In the real world of course many firms own some of their capital But for such a firm the market rental rate is the opportunity cost of using its own capital instead of renting it to another firm Hence R P is the relevant price in firms capital demand decisions whether firms own their capital or rent it CHAPTER 3CHAPTER 3National IncomeNational Income slide 16 Determining the rental rateDetermining the rental rate We have just seen that MPL W P The same logic shows that MPK R P diminishing returns to capital MPK as K The MPKcurve is the firm s demand curve for renting capital Firms maximize profits by choosing K such that MPK R P CHAPTER 3CHAPTER 3National IncomeNational Income slide 17 The equilibrium real rental rateThe equilibrium real rental rate The real rental rate adjusts to equate demand for capital with supply The real rental rate adjusts to equate demand for capital with supply Units of output Units of capital K MPK demand for capital equilibrium equilibrium R PR P Supply of capital K 7 CHAPTER 3CHAPTER 3National IncomeNational Income slide 19 How income is distributed How income is distributed total labor income If production function has constant returns to scale then total capital income W L P MPLL R K P MPKK YMPLLMPKK labor income capital income national income CHAPTER 3CHAPTER 3National IncomeNational Income slide 20 How income is distributed How income is distributed Note under the assumption of CRS and perfect competition there is no room for profits All the income produced is distributed to the factors of production What do firm owners eat Is this an implausible story Not really A firm is after all an entity where the owners put up some capital and where the managers are after all part of the work force hence labor CHAPTER 3CHAPTER 3National IncomeNational Income slide 21 How income is distributed How income is distributed Consequently the proper compensation for firm managers and firm owners is incorporated in the labor s and capital s payments MPL L andMPK K 8 CHAPTER 3CHAPTER 3National IncomeNational Income slide 22 Outline of modelOutline of model A closed economy market clearing model Supply side factor markets supply demand price determination of output income Demand side determinants of C I and G Equilibrium goods market loanable funds market DONE DONE Next CHAPTER 3CHAPTER 3National IncomeNational Income slide 23 Demand for goods servicesDemand for goods services Components of aggregate demand C consumer demand for g s I demand for investment goods G government demand for g s closed economy no NX CHAPTER 3CHAPTER 3National IncomeNational Income slide 24 Demand for goods servicesDemand for goods services For each component of demand we have to specify behavioral hypotheses what drives households consumption What makes firm decide to invest in new capital How does the government decide on spending and taxation 9 CHAPTER 3CHAPTER 3National IncomeNational Income slide 25 Consumption Consumption C C def disposable income is total income minus total taxes Y T Consumption function C C Y T Shows that Y T C Example C a c Y T ais that level of consumption an individual needs regardless of her disposable income subsistence level of consumption cmeasures the marginalincrease in consumption due to an increase in disposable income We refer to c as the marginal propensity to consumption CHAPTER 3CHAPTER 3National IncomeNational Income slide 26 The consumption functionThe consumption function C Y T C Y T 1 MPC 0 MPC G budget surplus T G public saving When T 0 Look at the equilibrium condition in the LF market SYC YTG GS According to our model this policy which increases the budget deficit G T also reduces national saving 16 CHAPTER 3CHAPTER 3National IncomeNational Income slide 48 Playing with the model cont Playing with the model cont r S I 1S I r r1 I1 r2 2 which causes the real interest rate to rise I2 3 which reduces the level of investment 1 The increase in the deficit reduces saving 2S CHAPTER 3CHAPTER 3National IncomeNational Income slide 49 Playing with the modelPlaying with the model What happens if there is tax decrease T 0 Again look at the equilibrium condition in the LF market SYC YTG According to our model this policy which also increases the budget deficit G T reduces national saving as well Hence investment must decrease TCS CHAPTER 3CHAPTER 3National IncomeNational Income slide 50 Mastering the Mastering the loanableloanable funds modelfunds model 2 Things that shift the investment curve certain technological innovations to take advantage of the innovation firms must buy new investment goods tax laws that affect investment investment tax credit 17 CHAPTER 3CHAPTER 3National IncomeNational Income slide 51 An increase in investment demandAn increase in investment demand An increase in desired investment r S I I1 S I2 r1 r2 raises the interest rate But the equilibrium level of investment cannot increase because the supply of loanable funds is fixed CHAPTER 3CHAPTER 3National IncomeNational Income slide 54 Chapter summaryChapter summary 1 Total output is determined b