1、slide 0Learning objectivesThis chapter introduces you to (1)the issues that macroeconomists study; (2)the tools that macroeconomists use; (3) some important concepts in macroeconomic analysis 宏观经济学家研究的问题；使用的工具；宏观经济分析中的一些重要概念slide 1Important issues in macroeconomics Why are millions of people unemplo
2、yed, even when the economy is booming? Why are there recessions? Can the government do anything to combat recessions? Should it?为何即使经济高涨的时候，也有大量劳动力失业？为什么有衰退？政府能做什么？该不该做？slide 2Important issues in macroeconomics What is the government budget deficit? How does it affect the economy? Why does the U.S.
3、have such a huge trade deficit? Why are so many countries poor? What policies might help them grow out of poverty?什么是政府预算赤字（budget deficit）？美国为什么有巨额赤字？为什么那么多的国家贫穷？什么样的政策可以帮助他们摆脱贫困？slide 33,0004,0005,0006,0007,0008,0009,00010,0001970197519801985199019952000U.S. Gross Domestic Product in billions of c
4、hained 1996 dollarslong-run upward trendGDPslide 43,0004,0005,0006,0007,0008,0009,00010,0001970197519801985199019952000U.S. Gross Domestic Product in billions of chained 1996 dollarsRecessionslongest economic expansion on record最长的经济扩张记录衰退slide 5Why learn macroeconomics?为什么学习宏观经济学？1.The macroeconomy
5、 affects societys well-being（社会福利）.example: Unemployment and social problems Each one-point increase in the u-rate（失业率） is associated with:920 more suicides（自杀者）650 more homicides（杀人者）4000 more people admitted to state mental institutions3300 more people sent to state prisons（监狱）37, 000 more deaths（
6、死亡）increases in domestic violence and homelessness（无家）可归）例如：失业和社会问题slide 6Why learn macroeconomics?2.The macroeconomy affects your well-being.Unemployment and earnings growth-5-4-3-2-101234519651970197519801985199019952000%growth rate of inflation-adjusted hourly earningschange in Unemployment rate每
7、小时工资增长率失业率失业率slide 7Why learn macroeconomics?2.The macroeconomy affects your well-being.Interest rates and mortgage paymentsFor a $150,000 30-year mortgage（抵押）: $9,888$8245.21%$11,520$9606.63%6/21/02annual paymentmonthly paymentactual rate on 30-year mortgagedate6/20/03slide 8Why learn macroeconomic
8、s?3.The macroeconomy affects politics & current events.Inflation and unemployment in election yearsyear U rate inflation rate elec. outcome19767.7%5.8%Carter (D)19807.1%13.5%Reagan (R)19847.5%4.3%Reagan (R)19885.5%4.1%Bush I (R)19927.5%3.0%Clinton (D)19965.4%3.3%Clinton (D)20004.0%3.4%Bush II (R)sli
9、de 9Economic models（经济模型）are simplified versions of a more complex reality irrelevant details are stripped awayUsed to （1）show the relationships between economic variables （2）explain the economys behavior （3）devise policies to improve economic performance不相干的细节都被剥离掉了是对真实世界的简化slide 10Example of a mod
10、el: The supply & demand for new cars explains the factors that determine the price of cars and the quantity sold assumes the market is competitive: each buyer and seller is too small to affect the market price Variables:Q d = quantity of cars that buyers demandQ s = quantity that producers supplyP =
11、 price of new carsY = aggregate income（外生变量）Ps = price of steel (an input) （外生变量）slide 11The demand for carsshows that the quantity of cars consumers demand is related to the price of cars and aggregate income. demand equation: (,)dQD P Yslide 12Digression: Functional notation General functional not
12、ation shows only that the variables are related:(,)dQD P YA list of the variables that affect Q dslide 13Digression: Functional notation General functional notation shows only that the variables are related:(,)dQD P Y A specific functional form shows the precise quantitative relationship:Examples:1)
13、 (,)60102dQD P YPY0.32) (,)dYQD P YPslide 14The market for cars: demandQ Quantity of carsP Price of carsDThe demand curve shows the relationship between quantity demanded and price, other things equal. demand equation: (,)dQD P Yslide 15The market for cars: supplyQ Quantity of carsP Price of carsDsu
14、pply equation: (,)ssQS P PSThe supply curve shows the relationship between quantity supplied and price, other things equal. slide 16The market for cars: equilibriumQ Quantity of carsP Price of carsSDequilibrium priceequilibriumquantityslide 17The effects of an increase in income:D2Q Quantity of cars
15、P Price of carsSD1Q1P1An increase in income increases the quantity of cars consumers demand at each price.which increases the equilibrium price and quantity.P2Q2demand equation: (,)dQD P Yslide 18The effects of a steel price increase:Q Quantity of carsP Price of carsS1DQ1P1An increase in Ps reduces
16、the quantity of cars producers supply at each pricewhich increases the market price and reduces the quantity.P2Q2S2supply equation: (,)ssQS P PPs = price of steel (an input)slide 19Endogenous vs. exogenous variables: The values of endogenous variables are determined in the model. The values of exoge
17、nous variables are determined outside the model: the model takes their values & behavior as given. In the model of supply & demand for cars,endogenous: , , dsPQQexogenous: , sYP内生变量对外生变量外生的Y = aggregate incomePs = price of steel (an input)slide 20Now you try:1.Write down demand and supply equations
18、for wireless phones; include two exogenous variables in each equation. 2.Draw a supply-demand graph for wireless phones.3.Use your graph to show how a change in one of your exogenous variables affects the models endogenous variables. slide 21A multitude of modelsNo one model can address all the issu
19、es we care about. For example, If we want to know how a fall in aggregate income affects new car prices, we can use the S/D model（供需模型） for new cars. But if we want to know why aggregate income falls, we need a different model. 没有一个模型是万能的，不同问题需要不同模型。slide 22A Multitude of Models So we will learn dif
20、ferent models for studying different issues (e.g., unemployment, inflation, long-run growth). For each new model, you should keep track of its assumptions（它的假定） , which of its variables are endogenous and which are exogenous（变量内生还是外生）,the questions it can help us understand, and those it cannot.slid
21、e 23Prices: flexible versus sticky Market clearing（市场出清）市场出清）: an assumption that prices are flexible and adjust to equate supply and demand. In the short run, many prices are sticky（粘性的）（粘性的）-they adjust only sluggishly（行动迟缓地） in response to supply/demand imbalances. For example, labor contracts th
22、at fix the nominal wage for a year or longer magazine prices that publishers change only once every 3-4 yearsslide 24Prices: flexible versus sticky The economys behavior depends partly on whether prices are sticky or flexible: If prices are sticky, then demand wont always equal supply. This helps ex
23、plainunemployment (excess supply of labor)the occasional inability of firms to sell what they produce. Long run: prices flexible, markets clear, economy behaves very differently 如果价格是粘性的，那么，需求不一定总是等于总供给。slide 25Outline of this book: Introductory material (Chaps. 1 & 2) Classical Theory （古典理论）(Chaps.
24、 3 to 6) How the economy works in the long run, when prices are flexible Growth Theory (Chaps. 7 to 8) （经济增长理论） The standard of living and its growth rate over the very long run Business Cycle Theory （经济周期理论(Chaps 9 to 13)How the economy works in the short run, when prices are sticky ）slide 26Outlin
25、e of this book: Policy debates (Chaps. 14 to15)Should the government try to smooth business cycle fluctuations? Is the governments debt(债务) a problem? Microeconomic foundations (Chaps. 16 to 19)Insights from looking at the behavior of consumers, firms, and other issues from a microeconomic perspecti
26、veslide 27Chapter summary1.Macroeconomics is the study of the economy as a whole, includinggrowth in incomes,changes in the overall level of prices,the unemployment rate.2.Macroeconomists attempt to explain the economy and to devise policies to improve its performance. 1、宏观经济研究经济整体：包括收入增长、价格水平全面变化、失
27、业率；2、解释经济并设计政策以改进绩效。slide 28Chapter summary3.Economists use different models to examine different issues.（使用数学模型来探讨不同问题）4.Models with flexible prices（易变价格模型） describe the economy in the long run; models with sticky prices（粘性价格模型） describe economy in the short run.5.Macroeconomic events and performance arise from many microeconomic transactions（微观经济交易）; so macroeconomics uses many of the tools of microeconomics（微观经济工具）.
