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1、Part A National Income: Where it Comes From and Where it Goes,3,周泳宏 暨南大学 经济学院,In this chapter, you will learn,what determines the economys total output/income how the prices of the factors of production are determined how total income is distributed what determines the demand for goods and services
2、how equilibrium in the goods market is achieved,The Circular Flow of Dollars Through the Economy,0,budget surplus 0,budget deficit,Outline of model,A closed economy, market-clearing model Supply side factor markets (supply, demand, price) determination of output/income Demand side determinants of C,
3、 I, and G Equilibrium goods market loanable funds market,3.1 Factors of production,K = capital: tools, machines, and structures used in production L = labor: the physical and mental efforts of workers,The production function,denoted Y = F(K, L) shows how much output (Y ) the economy can produce from
4、 K units of capital and L units of labor reflects the economys level of technology exhibits constant returns to scale,Determining output,we assume that the supplies of capital and labor and the technology are fixed, output is also fixed,3.2 The distribution of national income,The distribution of nat
5、ional income is determined by factor prices. factor prices the prices per unit that firms pay for the factors of production Wage price of L rental rate price of K,Since we have assumed that supply is fixed,How a Factor of Production Is Compensated,The factor demand curve determines the equilibrium f
6、actor price.,How dose it come?,Notation & Assumption,concepts W = 名义工资（ nominal wage ） R = 名义租金率（ nominal rental rate ） P = 产出的价格（ price of output ） W /P = 实际工资（ real wage which measured in units of goods rather than in dollars R /P = 实际租金（ real rental rate which measured in units of goods ） Assumpt
7、ion A competitive firm Facing a given W, R and P,1. Demand for labor,Marginal Product of Labor (MPL ) 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) 导数形式,Y output,MPL and the production function,L labor,MPL,diminishing
8、 marginal product,Exercise :,Which of these production functions have diminishing marginal returns to labor?,MPL and the demand for labor,Profit=Revenue - Cost = PMPL- W equilibrium： PMPL= W MPL= W/P,marginal product of labor equals the real wage.,Exercise,Prove Tips:,Max (Profit),MPL and the demand
9、 for labor,Each firm hires labor up to the point where MPL = W/P.,The equilibrium real wage,The real wage adjusts to equate labor demand with supply.,2. Determining 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 MP
10、K curve is the firms demand curve for renting capital. Firms maximize profits by choosing K such that MPK = R/P .,The equilibrium real rental rate,The real rental rate adjusts to equate demand for capital with supply.,The Neoclassical Theory of Distribution,states that each factor input is paid its
11、marginal product is accepted by most economists,How income is distributed:,total labor income =,If production function has constant returns to scale, then,total capital income =,constant returns to scale, profit maximization, and competition together imply that economic profit is zero.,In the real w
12、orld, firm owners and capital owners are usually the same people and, therefore, economic profit and the return to capital are often lumped together. If economic profit is zero, the “profit” in the national income accounts must be mostly the return to capital.,The ratio of labor income to total inco
13、me in the U.S.,Labors share of total income,Labors share of income is approximately constant over time. (Hence, capitals share is, too.), The ratio of labor income to total income in Chinese Provinces: 2009,中国统计年鉴2010，劳动者报酬地区生产总值，当年价,Discussion,以下事件对香港实际工资和资本实际租金的可能影响 假设在实施“输入内地专才计划”中，放宽内地“资讯科技及财经服务
14、方面专门人才”认定条件并简化申请程序。 假设在实施“输入内地专才计划”中，确实引入了大批香港稀缺人才。 进一步的思考：你要成为什么样的人才？,在Y = F(K, L)中，影响L？影响F？,Appendix： Returns to scale,Suppose Y1 = F (K1 , L1 ) Scale all inputs by the same factor z: K2 = zK1 & L2 = zL1 Y2 = F (K2, L2 )? Y2 = zY1 constant returns to scale Y2 zY1 increasing returns to scale Y2 zY1
15、 decreasing returns to scale,（链接：非正式资料：规模报酬与企业排名）,constant returns to scale for any z 0,Example,Now you try:,constant returns to scale,decreasing returns to scale （Z1）,increasing returns to scale （Z1）,constant returns to scale for any z 0,Appendix：The Cobb-Douglas Production Function,A is a paramete
16、r greater than zero that measures the productivity of the available technology. measures capitals share of income Capital Income = MPK x K = Y Labor Income = MPL x L = (1 )Y,Constant return to scale,Question:,Labor Income = MPL x L = (1 )Y Is there a positive relationship between wage and output?,中国统计年鉴，不变价（上年=100）,1995-2009,Table 3.1 Mankiw: Macroeconomics, Sixth Edition Copyright 2007 by Worth Publishers,U.S.A.,Homework,访问国家统计
