Model宏观经济学加州大学詹姆斯·布拉德福特·德

1、CHAPTER 6Building Blocks of the Flexible-Price Model1Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.QuestionsWhat is a full-employment analysis?What keeps the economy at full employment when wages and prices are flexible?What determines the level of consumption spending?What d

2、etermines the level of investment spending?2Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.QuestionsWhat determines the level of net exports?What determines the level of the exchange rate?3Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Full-Employment An

3、alysisWe will now look at the economy over the short-runa period in which its productive resources are fixedWe will assume that wages and prices are flexible so that all markets clearsupply equals demand in the labor marketfull-employment analysis4Copyright 2002 by The McGraw-Hill Companies, Inc. Al

4、l rights reserved.Flexible-Price ModelTwo sets of factors determine the levels of potential output and real wagesthe production functionthe balance of supply and demand in the labor market5Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Production FunctionPotential output (

5、Y*) is determined bythe size of the labor force (L)the economys capital stock (K)the efficiency of labor (E)a parameter indicating how quickly returns to investment diminish ()6Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.1 - The Production Function7Copyright 2002 b

6、y The McGraw-Hill Companies, Inc. All rights reserved.Flexible-Price ModelThe assumption that wages and prices are flexible was commonly made by “classical” economistsThus, this assumption is often called the classical assumptionguarantees that markets workguarantees full employmentguarantees that a

7、ctual output is equal to potential output8Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Flexible-Price ModelThe flexible-price assumption is not always a good onea market economy does not always produce full employmentThe “Keynesian” model assumes that wages and prices are st

8、ickythis will be covered in Section III of textThe Classical assumption simplifies the analysis of the economy9Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Table 6.1 - Classical Flexible-Price versus Keynesian Sticky-Price Analyses10Copyright 2002 by The McGraw-Hill Companie

9、s, Inc. All rights reserved.The Labor MarketAssume there are K identical firmseach firm owns one unit of the economys capital stockeach firm hires L workers and pays them the same wage Weach firm sells Y units of output at a per-unit price of Pno firm has control over the price it receives or the wa

10、ge it paysthese are determined by the market11Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketTo determine how many workers to hire, the firm follows two ruleshire workers to boost outputstop hiring when the extra revenue from the output hired by the last worker

11、 just equals his or her wage12Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketThe value of the output produced by the last worker hired is the product price (P) multiplied by the marginal product of labor (MPL)The cost of hiring the last worker is his or her wag

12、e (W)The firm will keep hiring until13Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketThe marginal product of labor is the difference between what the firm can produce with its current labor force (Lfirm) and what it could produce if it hired one more workerAt i

13、ts current labor force, the output of the firm will be14Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketTherefore, the marginal product of labor (MPL) must be equal to15Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.2 - The Firms

14、Output as a Function of the Firms Employment16Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketUsing the Cobb-Douglas form of the production functionSince Kfirm=117Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketThe term in t

15、he brackets is a growth rate of a variable raised to a power18Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketThe firm hires workers up to the point where the product price multiplied by the marginal product of labor equals the wageSubstituting for MPL19Copyrigh

16、t 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.3 - The Typical Firms Hiring Policy20Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketThe typical firms demand for labor isBecause there are K firms in the economy, total economy-wide employme

17、nt will be21Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketIf there are more workers than firms want to hire at the current wagesome of the unemployed will underbid their fellow employed workersthose who are employed will respond by accepting a lower wage to ke

18、ep their jobsreal wages will fall and firms will hire more workers22Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketIf there are fewer workers than firms want to hire at the current wagesome firms will try to bid workers away by offering higher wagesthe real wag

19、e will rise and firms will reduce the quantity of labor demandedEquilibrium occurs in the labor market when labor demand is equal to the labor force23Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.4 - Equilibrium in the Labor Market24Copyright 2002 by The McGraw-Hill

20、Companies, Inc. All rights reserved.The Labor MarketEquilibrium in the labor market means thatThis means that the equilibrium real wage is equal to25Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketWhen the labor market is in equilibrium, the typical firm produce

21、s an output level equal toTotal output will be K multiplied by the typical firms output26Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Labor MarketSimplifying, we get the Cobb-Douglas production functionIf markets work well, the actual level of output in the economy (Y) w

22、ill be equal to the economys potential output (Y*)27Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.5 - In a Full-Employment Economy, Real GDP Equals Potential Output28Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Domestic SpendingNational incom

23、e can be divided into four componentsconsumption spending (C)investment spending (I)government purchases (G)net exports (NX)29Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.6 - The Four Components of Spending Add Up to Real GDP30Copyright 2002 by The McGraw-Hill Compa

24、nies, Inc. All rights reserved.Consumption SpendingHouseholds use income (Y) in three wayspay net taxes (T)assume that T = t Y, where t is an average tax ratedisposable income is equal to income minus taxes YD = Y-T = (1-t)Ysave (SH)consume (C)31Copyright 2002 by The McGraw-Hill Companies, Inc. All

25、rights reserved.Figure 6.7 - From National Income to Consumption Spending32Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Consumption SpendingConsumption spending can be broken down into two componentsa baseline level of consumption (C0)the amount that households would spend o

26、n consumption goods if they had no income a fraction of disposable income (Cy YD)Cy is the marginal propensity to consume, amount by which consumption spending rises in response to a $1 increase in disposable income33Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Consumption S

27、pendingConsumption is assumed to be a linear function of real GDP (Y)There are other factors that affect consumption besides disposable incomeassumed to affect baseline consumption (C0) only34Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.8 - Other Determinants of Con

28、sumption Spending35Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Consumption SpendingCy is the marginal propensity to consume0Cy1if incomes rise, households will use some of their extra income to increase their consumption spendingas incomes rise, households will also increas

29、e their saving36Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.9 - The Consumption Function37Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Consumption SpendingExamplethe tax rate (t) = 25%, national income (Y) = $10 trillion, the baseline level

30、 of consumption (C0) = $2 trillion, and the marginal propensity to consume (Cy) = 0.6 38Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Investment SpendingFluctuations in investment spending have two sourcesthe interest ratea higher real interest rate makes investment projects

31、more expensive and lowers investmentbusiness managers and investors confidencethe higher their confidence, the higher is investment spending39Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Investment SpendingFirms invest because their managers believe that the investment proje

32、cts will be profitablethis means that the discounted returns on the investments must be greater than the investments coststhe most relevant interest rate for determining the profitability of an investment is the long-term, real, risky interest rate 40Copyright 2002 by The McGraw-Hill Companies, Inc.

33、 All rights reserved.Investment SpendingInvestment spending has two componentsthe baseline level of investment (I0)the responsiveness of investment to changes in the interest rate (Ir)41Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.10 - The Investment Function42Copyr

34、ight 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Investment SpendingExamplethe baseline level of investment (I0) = $2 trillion, the interest-sensitivity of investment (Ir) = $10 trillion, and the real interest rate = 5%43Copyright 2002 by The McGraw-Hill Companies, Inc. All rights re

35、served.Investment SpendingAn alternative way of looking at investment is to see the level of investment as a function of the level of the stock marketThe same things that determine the value of the stock market also determine the level of investmentexpected future profits (confidence)the real intere

36、st rate44Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Government PurchasesGovernment purchases (G) include purchases of labor and other goods and services by federal, state, and local governmentsGovernment purchases do not include transfer paymentstransfer payments are negat

37、ive taxesEconomists do not inquire into what determines G (or the tax rate t)45Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.11 - Government Purchases, Transfer Payments, and Taxes46Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.International T

38、radeNet exports (NX) is the difference between gross exports (GX) and imports (IM)47Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.12 - Gross Exports, Imports, andNet Exports48Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Gross ExportsThe volum

39、e of gross exports (GX) depends on two variablesthe real GDP of the countrys trading partners (Yf)the real exchange rate ()Xyf is the increase in exports generated by an increase in foreign GDPX is the increase in exports from an increase in the real exchange rate49Copyright 2002 by The McGraw-Hill

40、Companies, Inc. All rights reserved.Figure 6.13 - Gross U.S. Exports and the Real Exchange Rate, 1980-199050Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Gross ExportsIn the real world, there are substantial lags that occur between changes in the real exchange rate and change

41、s in the level of gross exportsa change in the real exchange rate this year will have little or no effect on gross exports this year, but will have effects on gross exports one, two, and three years into the future51Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Figure 6.14 -

42、The J-Curve in the 1980s52Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Gross ImportsThe value of demand for imports depends on domestic real GDP (Y)The quantity of imports demanded depends also on the real exchange rate ()however, the value of imports is largely independent

43、of the real exchange rategross imports will be a constant share of real GDP53Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Net ExportsNet exports (NX) are the difference between gross exports (GX) and imports (IM)Net exports depend on three thingsthe real exchange rate ()the

44、level of real GDP abroad (Yf)the level of real GDP at home (Y)54Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Exchange RateThe lives of foreign exchange speculators are ruled by fear and greeda higher U.S. interest rate means that an individual can profit from buying U.S.

45、 bondsthe greater this interest differential, the higher the greed factorif the U.S. real exchange rate rises, profits from holding U.S. bonds will be lowerthe higher the greed factor, the lower must be the exchange rate in order for fear to offset the greed55Copyright 2002 by The McGraw-Hill Compan

46、ies, Inc. All rights reserved.Figure 6.15 - Greed and Fear in Foreign Exchange Markets56Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.The Exchange RateThe real exchange rate is determined by two componentsthe average foreign exchange traders opinion of what the exchange rate

47、should be if there was no interest differential (0)the sensitivity of the exchange rate (r) to the interest rate differential between domestic real interest rates (r) and foreign real interest rates (rf)57Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Net ExportsSubstituting i

48、n for the real exchange rate, we getHaving the definition of net exports in this form tells us directly how domestic and foreign interest rates affect net exports58Copyright 2002 by The McGraw-Hill Companies, Inc. All rights reserved.Chapter SummaryWhen the economy is at full employment, the level of real GDP is equal to potential output-the level of output generated by the aggregate production function, given the current stocks of labor and capital and the current level of the efficiency of labor59Copyright 2002 by The McGraw-Hi