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1、Overviewpart4,Inthispartwewillstudyshort-termfluctuationsineconomicactivity,commonlyknownasrecessionsandexpansions.causeofshort-termfluctuationstheavailablepolicyresponses.,Short-TermEconomic Fluctuations:An Introduction,Chapter Outline,presents some background on the history characteristics of shor
2、t-term economic fluctuations.,Important Concepts Covered,Recession/depression 衰退/萧条Peak/trough 波峰/波谷Expansion/boom 扩张/繁荣Potential output 生产能力Output gap 产出缺口Recessionary and expansionary gap 衰退型和扩张型产出缺口Natural rate of unemployment 自然失业率Okuns Law 奥肯法则,.Recessions and Expansions,Recession(or contractio
3、n)A period in which the economy is growing at a rate significantly below normalDepressionA particularly severe or protracted recession,PeakThe beginning of a recession,the high point of economic activity prior to a downturnTroughThe end of a recession,the low point of economic activity prior to a re
4、covery,ExpansionA period in which the economy is growing at a rate significantly above normalBoomA particularly strong and protracted expansion,Fluctuations in U.S.Real GDP,1920-2004,U.S.Recessions Since 1929,Peak date(beginning),Trough date(end),Duration(months),Highest unemployment rate(%),Change
5、in real GDP(%),Duration of subsequent expansion(months),Aug.1929Mar.19334324.9-28.850May 1937June 19381319.0-5.580Feb.1945Oct.194583.9-8.537Nov.1948Oct.1949115.9-1.445July 1953May 1954105.5-1.239Aug.1957Apr.195886.8-1.724Apr.1960Feb.1961106.72.3106Dec.1969Nov.1970115.90.136Nov.1973Mar.1975168.5-1.15
6、8Jan.1980July 198067.6-0.312July 1981Nov.1982169.7-2.192July 1990Mar.199187.5-0.9120Mar.2001Nov.2001 85.80.8,.Some Facts About Short-term Economic Fluctuations,Economic fluctuations are:Irregular in length and severity.Felt throughout the economy and may have a global effect,Real GDP Growth in Five
7、Major Countries,1999-2004,Unemployment is a key indicator of short-term economic fluctuations.Industries that produce durable goods are more affected than nondurable&service industries.,Recessions are usually followed by a decline in inflation and many have been preceded by an increase in inflation.
8、,U.S.Inflation,1960-2004,.Output Gaps andCyclical Unemployment,Potential OutputOutput GapThe Natural Rate of UnemploymentOkuns Law,Potential Output,Y*(or potential real GDP or full-employment output)The maximum sustainable amount of output(real GDP)that an economy can produce,Output GapY*(potential
9、output)-Y(actual output)The difference between the economys potential output and its actual output at a point in time,Recessionary GapY*YA positive output gap,which occurs when potential output exceeds actual outputCapital and labor resources are not fully utilizedOutput and employment are below nor
10、mal levels,Expansionary GapY Y*A negative output gap,which occurs when actual output is higher than potential outputHigher output and employment than normalDemand for goods exceed the capacity to produce them and prices riseHigh inflation reduces economic efficiency,The Natural Rate of Unemployment
11、and Cyclical UnemploymentRecessionary gaps are characterized by high unemployment.Expansionary gaps are characterized by unusually low unemployment.,Types of unemployment(revisited)FrictionalStructuralCyclical,The Natural Rate of Unemployment and Cyclical UnemploymentNatural rate of unemployment,u*A
12、ttributable to frictional and structural unemploymentCyclical unemployment equals zeroNo recessionary or expansionary gapCyclical unemployment=u-u*total unemployment=natural rate,During recessionary gaps:u u*and cyclical unemployment is positiveDuring expansionary gaps:u u*and cyclical unemployment
13、is negative,Okuns LawEach extra percentage point of cyclical unemployment is associated with about a 2 percentage point increase in the output gap,measured in relation to potential output,Okuns Law(Y-Y*)/Y*=-a(u-u*),Okuns Law and the Output Gap in the U.S.Economy,Year,u,u*,Y*,19829.7%6.1%5,58419916.
14、85.87,30519984.55.28,95020025.85.210,342,1982 u-u*=cyclical unemployment 9.7-6.1=3.6%Output gap=2 x 3.6=7.2%Output gap=5,584 x.072=$402 billion,1991 6.8-5.8=1%Output gap=7,305 x.02=$146 billion,Okuns Law and the Output Gap in the U.S.Economy,Year,u,u*,Y*,19829.7%6.1%5,58419916.85.87,30519984.55.28,9
15、5020025.85.210,342,1998 4.5-5.2=-0.7 Output gap=8,563 x-.014=-$120 billion,2002 5.8-5.2=0.6 Output gap=10,342 x.012=$124 billion,Okuns LawThe 1982 output gap per capita$402 billion/230 million=$1,748 for a family of fourIn 2000 dollars it equals$7,000 for a family of four,.Why Do Short-Term Fluctuat
16、ions Occur?A Preview and a Parable,Why Do Short-Term Fluctuations Occur?Prices may not adjust in the short-run and firms adjust output to meet demand.When firms meet demand at preset prices,changes in economywide spending are the primary cause of output gaps.,Firms will eventually adjust prices to eliminate output gaps.In the long-run,output is determined by productive capacity and spending influences only inflation.,End ofChapter,
