专业课资料 练习题 真题 曼昆宏观英文版讲义 Ecn101_lecture5

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 5 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 Appendix to Chapter 3 pp 71 73 Jump to Chapter 7 pp 180 195 2 3 Reading for next class Chapter 7 pp 180 205 CHAPTER 3CHAPTER 3National IncomeNational Income slide 4 From last time From last time CHAPTER 3CHAPTER 3National IncomeNational Income slide 5 The market for goods servicesThe market for goods services The real interest rate adjusts to equate demand with supply The real interest rate adjusts to equate demand with supply Agg demand C YTI rG Agg supply YF K L Equilibrium YC YTI rG 3 CHAPTER 3CHAPTER 3National IncomeNational Income slide 6 The The loanableloanable funds marketfunds market A simple supply demand model of the financial system One asset loanable funds demand for funds investment supply of funds saving price of funds real interest rate CHAPTER 3CHAPTER 3National IncomeNational Income slide 7 Demand for funds InvestmentDemand for funds Investment The demand for loanable funds comes from investment Firms borrow to finance spending on plant equipment new office buildings etc Consumers borrow to buy new houses depends negatively on r the price of loanable funds the cost of borrowing CHAPTER 3CHAPTER 3National IncomeNational Income slide 8 LoanableLoanable funds demand curvefunds demand curve r I I r The investment curve is also the demand curve for loanable funds 4 CHAPTER 3CHAPTER 3National IncomeNational Income slide 9 Supply of funds SavingSupply of funds Saving The supply of loanable funds comes from saving Households use their saving to make bank deposits purchase bonds and other assets These funds become available to firms to borrow to finance investment spending The government may also contribute to saving if it does not spend all of the tax revenue it receives CHAPTER 3CHAPTER 3National IncomeNational Income slide 10 Types of savingTypes of saving private saving Y T C public saving T G national saving S private saving public saving Y T C T G Y C G CHAPTER 3CHAPTER 3National IncomeNational Income slide 11 LoanableLoanable funds supply curvefunds supply curve r S I SYC YTG National saving does not depend on r so the supply curve is vertical 5 CHAPTER 3CHAPTER 3National IncomeNational Income slide 12 LoanableLoanable funds market equilibriumfunds market equilibrium r S I I r SYC YTG Equilibrium real interest rate Equilibrium level of investment CHAPTER 3CHAPTER 3National IncomeNational Income slide 13 The special role of The special role of r r radjusts to equilibrate the goods market and the loanable funds market simultaneously If L F market in equilibrium then S Y C G I Add C G to both sides to get Y C I G goods market eq m Thus radjusts to equilibrate the goods market and the loanable funds market simultaneously If L F market in equilibrium then S Y C G I Add C G to both sides to get Y C I G goods market eq m Thus Eq m in L F market Eq m in goods market CHAPTER 3CHAPTER 3National IncomeNational Income slide 14 Digression mastering modelsDigression mastering models To learn a model well be sure to know 1 Which of its variables are endogenous and which are exogenous 2 For each curve in the diagram know a definition b intuition for slope c all the things that can shift the curve 3 Use the model to analyze the effects of each item in 2c 6 CHAPTER 3CHAPTER 3National IncomeNational Income slide 15 Mastering the Mastering the loanableloanable funds modelfunds model 1 Things that shift the saving curve public saving fiscal policy changes in Gor T private saving preferences tax laws that affect saving 401 k IRA replace income tax with consumption tax CHAPTER 3CHAPTER 3National IncomeNational Income slide 16 Playing with the modelPlaying with the model What happens if there is an increase in say defense spending G 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 Hence investment must decrease CHAPTER 3CHAPTER 3National IncomeNational Income slide 17 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 7 CHAPTER 3CHAPTER 3National IncomeNational Income slide 18 Playing with the modelPlaying with the model What happens if there is tax decrease T G budget surplus T G public saving When T 0 Again look at the equilibrium condition in the LF market SYC YTG According to our model this policy which does not affect the government budget still reduces national saving Hence investment must decrease 0 0 Pick z 1 L Then Y L F K L 1 y F k 1 y f k where f k F k 1 CHAPTER 7CHAPTER 7Economic Growth IEconomic Growth I slide 49 The production functionThe production function Output per worker y Capital per worker k f k Note this production function exhibits diminishing MPK Note this production function exhibits diminishing MPK 1 MPK f k 1 f k Please note variables on the axes are not the same as in the graph from CH 3 Here variables are in per capita terms CHAPTER 7CHAPTER 7Economic Growth IEconomic Growth I slide 50 The national income identityThe national income identity Y C I remember no G In per worker terms y c i where c C Land i I L 18 CHAPTER 7CHAPTER 7Economic Growth IEconomic Growth I slide 51 The consumption functionThe consumption function s the saving rate 0 s 1 the fraction of income that is saved sis an exogenous parameter Note Note s s is the only lowercase variable is the only lowercase variable that is not equal to that is not equal to its uppercase version divided by its uppercase version divided by L L Consumption function c 1 s y per worker CHAPTER 7CHAPTER 7Economic Growth IEconomic Growth I slide 52 Saving and investmentSaving and investment saving per worker y c y 1 s y sy National income identity is y c i Rearrange to get i y c sy investment saving like in chap 3 Using the results above i sy sf k CHAPTER 7CHAPTER 7Economic Growth IEconomic Growth I slide 53 Output consumption and investmentOutput consumption and investment Output per worker y Capital per worker k f k sf k k1 y1 i1 c1 19 CHAPTER 7CHAPTER 7Economic Growth IEconomic Growth I slide 54 DepreciationDepreciation Depreciation per worker k Capital per worker k k the rate of depreciation the fraction of the ca