7消费者生产者与生产效率英文版.ppt

2015 CUFEC H A P T E RConsumers,Producers,and the Efficiency of Markets7消费者、生产者消费者、生产者与市场效率与市场效率In this chapter,look for the answers to these questions:What is consumer surplus(消费者剩余)?How is it related to the demand curve?What is producer surplus（生产者剩余）?How is it related to the supply curve?Do markets produce a desirable allocation of resources（市场配置资源的合意配置）?Or could the market outcome be improved upon?1Some normative questionsThe consumers hope for a lower price all the time,and the producers hope for a higher price.Should the price be lower or higher?What is the“good”price?What is the proper way to use the resource?Who should consume more goods?Is clearance（出清）the best result of market?What is the value of the market?CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS2CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS3Is market economy good?The allocation of resources（资源配置）refers to:how much of each good is producedwhich producers produce itwhich consumers consume itIn market economies,the forces of supply and demand determine the prices of goods and services and the quantities sold.The market could clear by itself,but is it a good result?CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS4Welfare Economics 福利经济学福利经济学Welfare economics studies how the allocation of resources affects economic well-being（经济福利）.What benefits do the buyers and sellers get from taking part in a market?What are the total benefits of the market?How society can make these benefits as large as possible?A profound conclusion:The equilibrium of supply and demand in a market maximizes the total benefits received by buyers and sellers.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS5Willingness to Pay and Value 买者的支付意愿和价值买者的支付意愿和价值A buyers willingness to pay(WTP)for a good is the maximum amount the buyer will pay for that good.WTP measures how much the buyer values the good.nameWTPAnthony安东尼$250Chad 查德175Flea300John125Example:4 buyers WTP for an iPodCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS6WTP and the Demand CurveQ:If price of iPod is$200,who will buy an iPod,and what is quantity demanded?A:Anthony&Flea will buy an iPod,Chad&John will not.Hence,Qd=2 when P=$200.nameWTPAnthony$250Chad175Flea300John125CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS7WTP and the Demand CurveDerive the demand schedule:4John,Chad,Anthony,Flea 0 1253Chad,Anthony,Flea126 1752Anthony,Flea176 2501Flea251 3000nobody$301&upQdwho buysP(price of iPod)nameWTPAnthony$250Chad175Flea300John125CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS8WTP and the Demand CurvePQd$301&up0251 3001176 2502126 1753 0 1254PQCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS9About the Staircase ShapeThis D curve looks like a staircase with 4 steps one per buyer.PQIf there were a huge#of buyers,as in a competitive market,there would be a huge#of very tiny steps,and it would look more like a smooth curve.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS10WTP and the Demand CurveAt any Q,the height of the D curve is the WTP of the marginal buyer 边际购买者边际购买者 the buyer who would leave the market if P were any higher.PQFleas WTPAnthonys WTPChads WTPJohns WTPCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS11Consumer Surplus(CS)消费者剩余消费者剩余 Consumer surplus is the amount a buyer is willing to pay minus the amount the buyer actually pays:CS =WTP PnameWTPAnthony$250Chad175Flea300John125Suppose P=$260.Fleas CS=$300 260=$40.The others get no CS because they do not buy an iPod at this price.Total CS=$40.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS12CS and the Demand CurvePQFleas WTPP=$260 Fleas CS=$300 260=$40Total CS=$40CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS13CS and the Demand CurvePQFleas WTPAnthonys WTPInstead,suppose P=$220 Fleas CS=$300 220=$80Anthonys CS=$250 220=$30Total CS=$110CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS14CS and the Demand CurvePQThe lesson:Total CS equals the area under the demand curve above the price,from 0 to Q.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS15PQ$CS with Lots of Buyers&a Smooth D CurveThe demand for shoesD1000s of pairs of shoesPrice per pairAt Q=5(thousand),the marginal buyer is willing to pay$50 for pair of shoes.Suppose P=$30.Then his consumer surplus=$20.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS16PQCS with Lots of Buyers&a Smooth D CurveThe demand for shoesDCS is the area b/w P and the D curve,from 0 to Q.Recall:area of a triangle equals x base x heightHeight=$60 30=$30.So,CS=x 15 x$30 =$225.h$CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS17PQHow a Higher Price Reduces CSDIf P rises to$40,CS=x 10 x$20 =$100.Two reasons for the fall in CS.1.Fall in CS due to buyers leaving market2.Fall in CS due to remaining buyers paying higher P Some notes on CSThe CS equals to WTP minus the actual pay.it measures the benefit that buyers receive from a good as the buyers themselves perceive it.消费者剩余，即买者愿意为一种物品支付的量减他们实际支付的量，衡量了消费者从一种物品中得到的买者自己感觉到的利益。CS is a good measure if preferences of buyers should be respected all the time.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS18But,sometimes,the WTP(perceived value,感知 价值)may be different from the real value.The CS is not a good measure in this case.In most case,especially under the rational assumption,CS works quite well.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS1920PQdemand curveA.Find marginal buyers WTP at Q=10.B.Find CS for P=$30.Suppose P falls to$20.How much will CS increase due to C.buyers entering the marketD.existing buyers paying lower price$A C T I V E L E A R N I N G A C T I V E L E A R N I N G 1 1 Consumer surplusA C T I V E L E A R N I N G A C T I V E L E A R N I N G 1 1 Answers21P$Qdemand curveA.At Q=10,marginal buyers WTP is$30.B.CS=x 10 x$10=$50P falls to$20.C.CS for the additional buyers=x 10 x$10=$50D.Increase in CS on initial 10 units=10 x$10=$100CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS22Cost and the Supply CurvenamecostJack 杰克$10Janet 珍妮特20Chrissy 克丽希35A seller will produce and sell the good/service only if the price exceeds his or her cost.Hence,cost is a measure of willingness to sell.Cost is the value of everything a seller must give up to produce a good(i.e.,opportunity cost).Includes cost of all resources used to produce good,including value of the sellers time.Example:Costs of 3 sellers in the lawn-cutting（修草）business.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS23Cost and the Supply Curve335&up220 34110 190$0 9QsPDerive the supply schedule from the cost data:namecostJack$10Janet20Chrissy35CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS24Cost and the Supply CurvePQPQs$0 9010 19120 34235&up3CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS25Cost and the Supply CurvePQAt each Q,the height of the S curve is the cost of the marginal seller（边际卖家）（边际卖家）,the seller who would leave the market if the price were any lower.Chrissys costJanets costJacks costCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS26Producer Surplus 生产者剩余生产者剩余PQProducer surplus(PS):the amount a seller is paid for a good minus the sellers cost生产者剩余卖者得到的量减去卖者的成本。PS=P costCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS27Producer Surplus and the S CurvePQSuppose P=$25.Jacks PS=$15Janets PS=$5Chrissys PS=$0Total PS=$20Janets珍妮特costJacks杰克costTotal PS equals the area above the supply curve under the price,from 0 to Q.Chrissys 克丽希costPS=P costCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS28PQPS with Lots of Sellers&a Smooth S CurveThe supply of shoesS1000s of pairs of shoesPrice per pairSuppose P=$40.At Q=15(thousand),the marginal sellers cost is$30,and her producer surplus is$10.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS29PQPS with Lots of Sellers&a Smooth S CurveThe supply of shoesSPS is the area b/w P and the S curve,from 0 to Q.The height of this triangle is$40 15=$25.So,PS=x b x h =x 25 x$25 =$312.50hCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS30PQHow a Lower Price Reduces PSIf P falls to$30,PS=x 15 x$15 =$112.50Two reasons for the fall in PS.S1.Fall in PS due to sellers leaving market2.Fall in PS due to remaining sellersgetting lower PPQsupply curveA.Find marginal sellers cost at Q=10.B.Find total PS for P=$20.Suppose P rises to$30.Find the increase in PS due to C.selling 5 additional unitsD.getting a higher price on the initial 10 units31A C T I V E L E A R N I N G A C T I V E L E A R N I N G 2 2 Producer surplusA C T I V E L E A R N I N G A C T I V E L E A R N I N G 2 2 AnswersPQsupply curveA.At Q=10,marginal cost=$20 B.PS=x 10 x$20 =$100P rises to$30.C.PS on additional units=x 5 x$10=$25D.Increase in PS on initial 10 units=10 x$10=$10032CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS33CS,PS,and Total Surplus消费者剩余，生产者剩余，总剩余消费者剩余，生产者剩余，总剩余CS =(value to buyers)(amount paid by buyers)=buyers gains from participating in the marketPS =(amount received by sellers)(cost to sellers)=sellers gains from participating in the marketTotal surplus=CS+PS=total gains from trade in a market=(value to buyers)(cost to sellers)CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS34PQ$DSCS of single buyerPS of single sellerCS of all buyersPS of all sellersSurplus of the marketCS,PS,and Total Surplus消费者剩余，生产者剩余，总剩余消费者剩余，生产者剩余，总剩余CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS35The Markets Allocation of ResourcesIn a market economy,the allocation of resources is decentralized（权力下放）,determined by the interactions of many self-interested buyers and sellers.Is the markets allocation of resources desirable（合意）?Or would a different allocation of resources make society better off?To answer this,we use total surplus as a measure of societys well-being,and we consider whether the markets allocation is efficient.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS36The Benevolent Social Planner好心的社会管理者好心的社会管理者The benevolent social planner is an all-knowing（全知）,all-powerful（全能）,well-intentioned dictator（目标明确的独裁者）.The planner wants to maximize the economic well-being of everyone in society.To achieve the aim,the planner must first decide how to measure the economic well-being of a society.One possible measure is the sum of consumer and producer surplus,which we call total surplus.the social planner might also care about equality,though the focus here is on efficiency.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS37EfficiencyAn allocation of resources is efficient if it maximizes total surplus.Efficiency means:The goods are consumed by the buyers who value them most highly.The goods are produced by the producers with the lowest costs.Raising or lowering the quantity of a good would not increase total surplus.=(value to buyers)(cost to sellers)Total surplusCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS38Evaluating the Market EquilibriumMarket eqm:P=$30 Q=15,000Total surplus =CS+PSIs the market eqm efficient?PQSDCSPSCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS39Which Buyers Consume the Good?PQSDEvery buyer whose WTP is$30 will buy.Every buyer whose WTP is$30 will not.So,the sellers with the lowest cost produce the good.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS41Does Eqm Q Maximize Total Surplus?PQSDAt Q=20,cost of producing the marginal unit is$35 value to consumers of the marginal unit is only$20Hence,can increase total surplus by reducing Q.This is true at any Q greater than 15.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS42Does Eqm Q Maximize Total Surplus?PQSDAt Q=10,cost of producing the marginal unit is$25 value to consumers of the marginal unit is$40Hence,can increase total surplus by increasing Q.This is true at any Q less than 15.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS43Does Eqm Q Maximize Total Surplus?PQSDThe market eqm quantity maximizes total surplus:At any other quantity,can increase total surplus by moving toward the market eqm quantity.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS44Price0QuantityEquilibriumquantitySupplyDemandCost to sellersValue to buyersValue to buyers Cost to sellersValue to buyers is greater than cost to sellers.Value to buyers is less than cost to sellers.The Efficiency of the Equilibrium QuantityCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS45Adam Smith and the Invisible Hand“Man has almost constant occasion for the help of his brethren,and it is vain for him to expect it from their benevolence only.Adam Smith,1723-1790Passages from The Wealth of Nations,1776 He will be more likely to prevail if he can interest their self-love in his favor,and show them that it is for their own advantage to do for him what he requires of themIt is not from the benevolence of the butcher,the brewer,or the baker that we expect our dinner,but from their regard to their own interest.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS46Adam Smith and the Invisible Hand“Every individualneither intends to promote the public interest,nor knows how much he is promoting it.Adam Smith,1723-1790Passages from The Wealth of Nations,1776He intends only his own gain,and he is in this,as in many other cases,led by an invisible hand to promote an end which was no part of his intention.Nor is it always the worse for the society that it was no part of it.By pursuing his own interest he frequently promotes that of the society more effectually than when he really intends to promote it.”an invisible handCONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS47The Free Market vs.Govt Intervention自由市场自由市场 Vs.政府干预政府干预The market equilibrium is efficient.No other outcome achieves higher total surplus.Govt cannot raise total surplus by changing the markets allocation of resources.Laissez faire,(French for“allow them to do”)自由主自由主义义:the notion that govt should not interfere with(干预干预)the market.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS48The Free Market vs.Central Planning自由市场自由市场 Vs.中央计划中央计划Suppose resources were allocated not by the market,but by a central planner who cares about societys well-being.To allocate resources efficiently and maximize total surplus,the planner would need to know every sellers cost and every buyers WTP for every good in the entire economy.This is impossible,and why centrally-planned economies are never very efficient.CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS49Discuss:Should There be a Market in Organs（器官）?On April 12,2001,the front page of the Boston Globe ran the headline“How a Mothers Love Helped Save Two Lives.”A woman whose named Susan Stephens has a son who needs a kidney transplant.When the doctor learned that the mothers kidney was not compatible（不相容）,he proposed a novel solution:If Stephens donated one of her kidneys to a stranger,her son would move to the top of the kidney waiting list.The mother accepted the deal,and soon two patients had the transplant they were waiting for.If the mother could trade a kidney for a kidney,would the hospital allow her to trade a kidney for something else?CONSUMERS,PRODUCERS,AND THE EFFICIENCY OF MARKETS50Case studyStrong Booze:Criminal Incentives烈酒：犯罪激励烈酒：犯罪激励During 1920s Prohibition,the sell,manufacture,and transportation of alcohol were restricted or illegal.Prohibition was supposed to