经原学习重点和难点.docx

经原学习重点和难点.docx

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经原学习重点和难点

小注一下～

1．这是04级师兄师姐在大一学习经济学原理的过程中自行总结归纳的一份材料，重难点都只是当时的个人取舍，不一定是testpoint。

2．图对于经原学习是极其重要的，但是由于作者不擅电脑绘图，这里没有配图，希望大家平时要多多动手画图哦！

！

！

3．文中提到的“英文Pxx”指英文版教材页码，“中文”指中文版。

“新编”指由盛晓白，黄健康主编，北京大学出版社出版的《微观经济学新编》，是作者在学习微观时使用的参考书。

个人觉得挺好～

4．由于作者水平有限，时间仓促，难免有错误和漏洞，希望大家可以多多指教

最后，希望大家学经原学得开心。

。

。

^_^。

Chapter3basicelementsofsupplyanddemand

Theoryofsupplyanddemand

Showshowconsumerpreferences（偏好）determineconsumerdemandforcommodities,whilebusinesscostsarethefoundationofthesupplyofcommodities.（商品）

Competitive（竞争的）equilibrium（均衡）

Thedemandcurvesandthesupplycurvesintersect（交叉）—theforcesofdemandandsupplyarejustinbalance.

DEMAND

Thedemandschedule（thedemandcurve）

Therelationshipbetweenpriceandquantitybought.

Demandcurve

Thegraphical（图示的）representationofthedemandschedule

Lawofdownward-slopingdemand需求向下倾斜规律

Whenthepriceofacommodityisraised（andotherthingsareheldconstant）,buyerstendtobuylessofthecommodity.

Substitutioneffect

Whenthepriceofagoodrises,peoplewillsubstituteothersimilargoodsforit.

Incomeeffect

Whenapricegoesup,peoplefindthemselvessomewhatpoorerthantheywerebefore.Theyhaveineffectlessrealincome.

Marketdemand

Representsthesumtotalofallindividualdemands

Aarrayoffactorsthatinfluenceshowmuchwillbedemandedatagivenprice—determinesthemarketdemand:

1.Objectiveelements:

1.1Averagelevelsofincome:

peopletendtobuymoreofalmosteverythingwhentheirincomesrise,evenifpricesdon’tchange.

1.2Sizeofthemarket:

measuredbypopulation,10peopletendtobuymorethan1people.

1.3Thepricesandavailabilityofrelatedgoods:

demandforoiltendstobelowifthepriceofnaturalgasislow.（substituteproduct）

2.Subjective（主观的）elements:

2.1Tastes

2.2Preferences

3.Specialinfluences:

thedemandforumbrellasishighinrainycitybutlowinsunnycity.Expectationsaboutfutureeconomicconditions,particularlyprices

SUPPLY

Thesupplyschedule（orsupplycurve）foracommodity

Showstherelationshipbetweenitsmarketpriceandtheamountofthatcommoditythatproducersarewillingtoproduceandsell,otherthingsheldconstant.

Elementsthataffectthesupplycurve:

1.Costofproduction

Onemajorelementunderlyingthesupplycurve,whichisprimarilydeterminedbythepricesofinputsandtechnologicaladvances

2.Thepricesofrelatedgoods

3.Governmentpolicy

4.Specialinfluences（weatherinfluencesfarming.

Shiftsinsupply

●Whenpriceofagoodchanges,producerschangetheirproductionandquantitysupplied—movealongthecurve,butthesupplyandthesupplycurvedonotshift.

●Whenotherinfluencesaffectingsupplychange,supplychangesandthesupplycurvesshifts.

Supplyincreases（ordecreases）whentheamountsuppliedincreases（ordecreases）ateachmarketprice.

EQUILIBRIUMOFSUPPLYANDDEMAND

Marketequilibrium

Comesatthatpriceandquantitywheretheforcesofsupplyanddemandareinbalance.

Theequilibriumpriceisalsocalledthemarket-clearingprice（市场出清价格）

Therearenoshortagesorsurpluses（剩余）attheequilibriumprice.

Whatthemarketmechanism（结构）accomplishes（实现）—rationing（限量）byprices（rationingbythepurse）

Whatgoodsareproduced?

Forwhomaregoodsproduced?

Howtoproduce?

WORDS

Individualcommodities单个商品

Marketmechanism市场机制

PARTTWOMICROECONOMICS:

SUPPLY,DEMAND,ANDPRODUCTMARKETS

Chapter4applicationsofsupplyanddemand

ELASTICITYOFDEMANDANDSUPPLY

§1.Priceelasticityofdemand（priceelasticity）

Measureshowmuchthequantitydemandedofagoodchangeswhenitspricechanges.

Thepercentagechangeinquantitydemandeddividedbythepercentagechangeinprice

Elasticity

Factor1

Factor2

Factor3

Elastic

Luxuries

Havesubstitutes

Havemoretimetoadjust

Inelastic

Necessities

Havenosubstitutes

Havelesstimetoadjust

*factor3:

thelengthoftimethatpeoplehaverespondtopricechanges

Plus:

4.支出占消费者收入比重小的商品需求价格弹性小；占比重大的商品需求价格弹性大。

5.数量越大，价格越低的商品价格弹性小；数量越小，价格越高的商品价格弹性大。

Calculatingelasticities

Priceelasticityofdemand=

ED=percentagechangeinquantitydemanded/percentagechangeinprice

●Price-elasticdemand:

A1percentchangeinpricecallsforthmorethana1percentchangeinquantitydemanded.

●Price-inelasticdemand

A1percentchangeinpriceevokes（引起）lessthana1percentchangeinquantitydemanded.

●Unit-elasticdemand

Thepercentagechangeinquantityisexactlythesameasthepercentagechangeinprice.

Thisconditionimpliesthattotalexpendituresonthecommodity（equalP*Q）staythesameevenwhenthepricechanges.

Threekeystepstocalculate（*1）

●计算需求曲线的价格弹性：

直线上任何一点的弹性等于位于该点之下的线段长度与位于该点之上的线段长度的比值。

Polar（极）extremes—thepriceelasticitiesareinfiniteorzero—completelyelasticandcompletelyinelastic

●Completelyinelasticdemand（withzeroelasticity）:

thequantitydemandedrespondsnotatalltopricechanges.（Vertical（垂直的）demandcurve）

需求量不随价格而变动

●Infinitely（无限的）elasticdemand:

atinychangeinpricewillleadtoanindefinitelylargechangeinquantitydemanded.（Horizontaldemandcurve）

价格一定，需求量可以是无限的

Warning:

elasticityisnotthesameasslope.（*2）

一般来说，在任何直线的中点M的上方，需求富有弹性，ED>1；中点处，需求具有单位弹性ED＝1；中点以下，需求缺乏弹性ED<1。

Elasticityandrevenue（收入）

Totalrevenue:

pricetimesquantity

●Whendemandisprice-inelasticapricedecreasededucestotalrevenue.

●Whendemandisprice-elastic,apricedeceaseincreasestotalrevenue.

●Intheborderlinecaseofunit-elasticdemand,apricedecreaseleadstonochangeintotalrevenue.

§2.Priceelasticityofsupply

Theresponsiveness（快速反应）ofthequantitysuppliedofagoodtoitsmarketprice

Thepercentagechangeinquantitysupplieddividedbythepercentagechangeinprice

Factorsthatdeterminesupplyelasticity:

1.Theeasewithwhichproductionintheindustrycanbeincreased行业中增加生产的困难程度

Whetheralltheinputscanbereadilyfoundatgoingmarketprices

纺织行业，价格的微小上升就会导致产出大幅度增加

Whethertheproductioncapacityisseverelylimited

南非金矿开采，即使黄金价格急剧上升，产量也只能增加少许

2.Thetimeperiodunderconsideration供给者做出反应时间的长短

给定的价格变动会对供给量产生较大的影响。

价格上升后的短暂时期内，企业也许无法增加其劳动、物资和资本投入，因此供给可能缺乏弹性；随着时间推移，企业可以雇佣更多工人，建造新的厂房和扩大生产能力——供给弹性变大。

BBB

APPLICATIONSTOCURRENTECONOMICISSUES

Long-runrelativedeclineoffarming农业的长期相对衰落

Sharpincreasesinsupplyoutpacedmodestincreasesindemand,producingadownwardtrendinfarmpricesrelativetootherpricesintheeconomy.

Manygovernmentsattempttohelpfarmersbyreducingtheirproduction.

Productionrestrictions（限制生产）aretypicalofgovernmentmarketinterferencesthatraisetheincomesofonegroupattheexpenseofothers.

●Thiskindofpolicyisinefficient:

thegaintofarmersisactuallylessthantheharmtoconsumers.

Incidence（归宿）

Theultimateeconomicimpactorburdenofatax（税赋的最终经济影响）

Whobearsthetrueburdenofatax?

—generalrulesontaxshifting（税收转嫁的一般原理）

Theincidenceofataxisdeterminedbytheeffectonpricesandquantitiesinsupply-and-demandequilibrium.

Ingeneral,theburdenorincidencedependsupontherelativeelasticitiesofdemandandsupply.

Ataxisshiftedforwardtoconsumersifthedemandisinelasticrelativetosupply.

Ataxisshiftedbackwardtoproducersifsupplyisrelativelymoreinelasticthandemand.

汽油的需求相对于供给缺乏弹性，则赋税的负担大部分转嫁给了消费者。

土地的供给相对于需求缺乏弹性，则税赋大部分转嫁给了供给者。

注：

汽油的例子

需求曲线没有移动，因为汽油税增加后在每一个零售价格水平上，需求量并没有变化。

供给曲线向上移动，因为只有当生产者得到与以前相等的净价格（thesamenetprice），他们才会愿意出售某个数量。

在每一供给量上，市场价格上升的幅度必须正好等于税额。

Subsidies（补贴）

Taxesareusedtodiscourageconsumptionofacommodity--gasoline.

Subsidiesareusedtoencourageproduction--agriculture.

Governmentsoccasionallyinterferewiththeworkingsofcompetitivemarketsbysettingmaximumceilingsorminimumfloorsonprices.Insuchsituations,quantitysuppliedneednolongerequalquantitydemanded.

Ceilingsleadtoexcessdemand（pricecontrolsproduceshortagesinthecaseofgasoline.

Floorsleadtoexcesssupply.

Theinterferencemayraisetheincomesofaparticulargroup（farmersorlow-skilledworkers）,butoftendistortionsandinefficienciesresults.Waste,inefficiency,andaggravation（短缺）arecertaincompanionsofsuchinterferences.

WORDS

Productmarkets产品市场

Chapter5demandandconsumerbehavior

●Economicsreliesonthefundamentalpremisethatpeopletendtochoosethosegoodsandservicestheyvaluemosthighly.

Utility

Denotessatisfaction,referstohowconsumersrankdifferentgoodsandservices

●Inthetheoryofdemand,wesaythatpeoplemaximizetheirutility,whichmeansthattheychoosethebundleofconsumptiongoodsthattheymostprefer.

Marginalutility

Denotestheadditionalutilityarisingfromconsumptionofanadditionalunitofacommodity

消费新增一单位商品时所带来的新增的效用

Lawofdiminishingmarginalutility

Statesthattheamountofextraormarginalutilitydeclinesasapersonconsumesmoreandmoreofagood

效用的单位是“尤特尔”（utils）

边际效用曲线必然向下倾斜；总效用曲线必然为反U形。

总效用是从开始处累计起来的所有边际效用之和。

图：

边际效用曲线之下的总面积等于消费单位数相同的总效用曲线的高度。

Equimarginalprinciple:

equalmarginalutilitiesperdollarforeverygood

Equimarginalprinciple等边际准则:

Thefundamentalconditionofmaximumsatisfactionorutility

Thefundamentalconditionofconsumerequilibrium消费者均衡的基本条件

Itstatesthataconsumerhavingafixedincomeandfacinggivenmarketpricesofgoodswillachievemaximumsatisfactionorutilitywhenthemarginalutilityofthelastdollarspentoneachgoodisexactlythesameasthemarginalutilityofthelastdollarspentonanyothergood.花费在任何一种物品上的最后一美元所得到的边际效用正好等于花费在其他任何一种物品上的最后一美元所得到的边际效用时，该消费者得到最大的满足或效用。

Marginalutilityofincome收入的边际效用:

Thecommonmarginalutilityperdollarofallcommoditiesinconsumerequilibrium

消费者均衡时，各种物品每一美元的一般边际效用

MUgood1/P1=MUgood2/P2=……=MUper$ofincome

●Whydemandcurvesslopedow