《北大微观经济学ch16Equilibrium课件》由会员分享，可在线阅读，更多相关《北大微观经济学ch16Equilibrium课件（93页珍藏版）》请在金锄头文库上搜索。
1、Chapter SixteenEquilibrium均衡均衡北大微观经济学ch16EquilibriumStructureuMarket equilibriumuQuantity tax and equilibriumuTax incidence （税收分担）税收分担）uDeadweight loss （额外净损失）额外净损失）北大微观经济学ch16EquilibriumMarket EquilibriumuA market is in equilibrium when total quantity demanded by buyers equals total quantity suppli
2、ed by sellers.uAlso called “market is cleared”uSupply may not equal production北大微观经济学ch16EquilibriumMarket EquilibriumpD(p), S(p)q=D(p)MarketdemandMarketsupplyq=S(p)北大微观经济学ch16EquilibriumMarket SettinguCompetitive marketContestable market北大微观经济学ch16EquilibriumMarket EquilibriumpD(p), S(p)q=D(p)Marke
3、tdemandMarketsupplyq=S(p)p*q*D(p*) = S(p*); the marketis in equilibrium.北大微观经济学ch16EquilibriumMarket EquilibriumpD(p), S(p)q=D(p)MarketdemandMarketsupplyq=S(p)p*S(p)D(p) S(p); an excessof quantity supplied overquantity demanded.pD(p)北大微观经济学ch16EquilibriumMarket EquilibriumpD(p), S(p)q=D(p)Marketdema
4、ndMarketsupplyq=S(p)p*S(p)D(p) S(p”); an excessof quantity demandedover quantity supplied.p”S(p”)北大微观经济学ch16EquilibriumMarket EquilibriumpD(p), S(p)q=D(p)MarketdemandMarketsupplyq=S(p)p*D(p”)D(p”) S(p”); an excessof quantity demandedover quantity supplied.p”S(p”)Market price must rise towards p*.北大微
5、观经济学ch16EquilibriumMarket Equilibrium Linear D & SAt the equilibrium price p*, D(p*) = S(p*).That is,which givesand北大微观经济学ch16EquilibriumMarket EquilibriumpD(p), S(p)D(p) = a-bpMarketdemandMarketsupplyS(p) = c+dp北大微观经济学ch16EquilibriumMarket EquilibriumuCan we calculate the market equilibrium using t
6、he inverse market demand and supply curves?uYes, it is the same calculation.北大微观经济学ch16EquilibriumMarket Equilibriumthe equation of the inverse marketdemand curve. Andthe equation of the inverse marketsupply curve.北大微观经济学ch16EquilibriumMarket EquilibriumqD-1(q),S-1(q)D-1(q) = (a-q)/bMarket inversede
7、mandS-1(q) = (-c+q)/dp*q*At equilibrium,D-1(q*) = S-1(q*).Market inverse supply北大微观经济学ch16EquilibriumMarket EquilibriumandAt the equilibrium quantity q*, D-1(p*) = S-1(p*).That is,which givesand北大微观经济学ch16EquilibriumMarket EquilibriumqD-1(q),S-1(q)D-1(q) = (a-q)/bMarketdemandMarketsupplyS-1(q) = (-c
8、+q)/d北大微观经济学ch16EquilibriumMarket EquilibriumuTwo special cases:lquantity supplied is fixed, independent of the market price, andlquantity supplied is extremely sensitive to the market price.北大微观经济学ch16EquilibriumMarket EquilibriumS(p) = c+dp, so d=0and S(p) c.pqq* = cMarket quantity supplied isfixe
9、d, independent of price.北大微观经济学ch16EquilibriumMarket EquilibriumS(p) = c+dp, so d=0and S(p) c.pqp*D-1(q) = (a-q)/bMarketdemandq* = cMarket quantity supplied isfixed, independent of price.北大微观经济学ch16EquilibriumMarket EquilibriumS(p) = c+dp, so d=0and S(p) c.pq p* =(a-c)/bD-1(q) = (a-q)/bMarketdemandq
10、* = cp* = D-1(q*); that is,p* = (a-c)/b.Market quantity supplied isfixed, independent of price.北大微观经济学ch16EquilibriumMarket EquilibriumS(p) = c+dp, so d=0and S(p) c.pqD-1(q) = (a-q)/bMarketdemandq* = cp* = D-1(q*); that is,p* = (a-c)/b.with d = 0 give p* =(a-c)/bMarket quantity supplied isfixed, ind
11、ependent of price.北大微观经济学ch16EquilibriumMarket EquilibriumMarket quantity supplied isextremely sensitive to price.S-1(q) = p*.pqp*北大微观经济学ch16EquilibriumMarket EquilibriumMarket quantity supplied isextremely sensitive to price.S-1(q) = p*.pqp*D-1(q) = (a-q)/bMarketdemandq*北大微观经济学ch16EquilibriumMarket
12、 EquilibriumMarket quantity supplied isextremely sensitive to price.S-1(q) = p*.pqp*D-1(q) = (a-q)/bMarketdemandq* =a-bp*p* = D-1(q*) = (a-q*)/b soq* = a-bp*北大微观经济学ch16EquilibriumComparative StaticsuShifting demand curvesIncomePrice of other productsuShifting supply curvesTechnologyuTaxes北大微观经济学ch16
13、EquilibriumQuantity TaxesuA quantity tax levied at a rate of $t is a tax of $t paid on each unit traded.uIf the tax is levied on sellers then it is an excise tax.uIf the tax is levied on buyers then it is a sales tax.北大微观经济学ch16EquilibriumQuantity TaxesuWhat is the effect of a quantity tax on a mark
14、ets equilibrium?uHow are prices affected?uHow is the quantity traded affected?uWho pays the tax?uHow are gains-to-trade altered?北大微观经济学ch16EquilibriumQuantity TaxesuA tax rate t makes the price paid by buyers, pb, higher by t from the price received by sellers, ps.北大微观经济学ch16EquilibriumQuantity Taxe
15、suEven with a tax the market must clear.uI.e. quantity demanded by buyers at price pb must equal quantity supplied by sellers at price ps.北大微观经济学ch16EquilibriumQuantity Taxesanddescribe the markets equilibrium.Notice that these two conditions apply nomatter if the tax is levied on sellers or onbuyer
16、s.Hence, a sales tax rate $t has thesame effect as an excise tax rate $t.北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*No tax北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*$tAn excise taxraises the mar
17、ketsupply curve by $t北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*An excise taxraises the marketsupply curve by $t,raises the buyersprice and lowers thequantity traded.$tpbqt北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)Marketd
18、emandMarketsupplyp*q*An excise taxraises the marketsupply curve by $t,raises the buyersprice and lowers thequantity traded.$tpbqtAnd sellers receive only ps = pb - t.ps北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*No tax北大微观经济学ch16EquilibriumQuantity
19、 Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*An sales tax lowersthe market demandcurve by $t$t北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*An sales tax lowersthe market demandcurve by $t, lowersthe sellers price andreduces the q
20、uantitytraded.$tqtps北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*An sales tax lowersthe market demandcurve by $t, lowersthe sellers price andreduces the quantitytraded.$tpbpbqtpbAnd buyers pay pb = ps + t.ps北大微观经济学ch16EquilibriumQuantity Taxes & Mar
21、ket EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*A sales tax levied atrate $t has the sameeffects on themarkets equilibriumas does an excise taxlevied at rate $t.$tpbpbqtpbps$t北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumuWho pays the tax of $t per unit traded?uThe division of the $
22、t between buyers and sellers is the incidence of the tax (税收分担税收分担).北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*pbpbqtpbps北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*pbpbqtpbpsTax paid by buyers北大
23、微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*pbpbqtpbpsTax paid by sellers北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumpD(p), S(p)MarketdemandMarketsupplyp*q*pbpbqtpbpsTax paid by buyersTax paid by sellers北大微观经济学ch16EquilibriumQuantity Tax
24、es & Market EquilibriumuE.g. suppose the market demand and supply curves are linear.北大微观经济学ch16EquilibriumQuantity Taxes & Market Equilibriumand北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumandWith the tax, the market equilibrium satisfiesandsoand北大微观经济学ch16EquilibriumQuantity Taxes & Mar
25、ket EquilibriumandWith the tax, the market equilibrium satisfiesandsoandSubstituting for pb gives北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumandgiveThe quantity traded at equilibrium is北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumAs t 0, ps and pb theequilibrium price ifther
26、e is no tax (t = 0) and qt the quantity traded at equilibriumwhen there is no tax.北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumAs t increases, ps falls,pb rises, andqt falls.北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumThe tax paid per unit by the buyer is北大微观经济学ch16Equilibri
27、umQuantity Taxes & Market EquilibriumThe tax paid per unit by the buyer isThe tax paid per unit by the seller is北大微观经济学ch16EquilibriumQuantity Taxes & Market EquilibriumThe total tax paid (by buyers and sellerscombined) is北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesuThe incidence o
28、f a quantity tax depends upon the own-price elasticities of demand and supply.北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtps北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsChan
29、ge to buyersprice is pb - p*.Change to quantitydemanded is q. q北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesAround p = p* the own-price elasticityof demand is approximately北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesAround p = p* the own-price elasticityof demand i
30、s approximately北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtps北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsChange to sellersprice is ps - p*.Change to quantitydemanded is q.
31、q北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesAround p = p* the own-price elasticityof supply is approximately北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesAround p = p* the own-price elasticityof supply is approximately北大微观经济学ch16EquilibriumTax Incidence and Own-Pri
32、ce ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*pbpbqtpbpsTax paid by buyersTax paid by sellers北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*pbpbqtpbpsTax paid by buyersTax paid by sellersTax incidence = 北大微观经济学ch16EquilibriumTax Incidence
33、 and Own-Price ElasticitiesTax incidence = 北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesTax incidence = So北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesTax incidence isThe fraction of a $t quantity tax paidby buyers rises as supply becomes moreown-price elastic or as
34、 demand becomesless own-price elastic.北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsAs market demandbecomes less own-price elastic, taxincidence shifts moreto the buyers. 北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p
35、), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsAs market demandbecomes less own-price elastic, taxincidence shifts moreto the buyers. 北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyps= p*$tpbqt = q*As market demandbecomes less own-price elastic, taxincid
36、ence shifts moreto the buyers. 北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyps= p*$tpbqt = q*As market demandbecomes less own-price elastic, taxincidence shifts moreto the buyers. When e eD = 0, buyers pay the entire tax, even though it is levied o
37、n the sellers.北大微观经济学ch16EquilibriumTax Incidence and Own-Price ElasticitiesTax incidence isSimilarly, the fraction of a $t quantitytax paid by sellers rises as supplybecomes less own-price elastic or asdemand becomes more own-price elastic.北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price Elastic
38、itiesuA quantity tax imposed on a competitive market reduces the quantity traded and so reduces gains-to-trade (i.e. the sum of Consumers and Producers Surpluses).uThe lost total surplus is the taxs deadweight loss（额外净损失）额外净损失）, or excess burden.北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price El
39、asticitiespD(p), S(p)MarketdemandMarketsupplyp*q*No tax北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*No taxCS北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*No taxPS北大微观经济学ch16EquilibriumD
40、eadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*No taxCSPS北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price Elasticities$tqtCSThe tax reducesboth CS and PSpD(p), S(p)MarketdemandMarketsupplyp*q*pbpsPS北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD
41、(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsCSPSThe tax reducesboth CS and PS,transfers surplusto governmentTax北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsCSPSThe tax reducesboth CS and PS,transfers surplusto governmentTax北大微观经济学ch1
42、6EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsCSPSThe tax reducesboth CS and PS,transfers surplusto governmentTax北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsCSPSThe tax reducesbo
43、th CS and PS,transfers surplusto government,and lowers total surplus.Tax北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q*$tpbqtpsDeadweight loss北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyp*q
44、*$tpbqtpsDeadweight loss fallsas market demandbecomes less own-price elastic.北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiespD(p), S(p)MarketdemandMarketsupplyps= p*$tpbqt = q*Deadweight loss fallsas market demandbecomes less own-price elastic.When e eD = 0, the tax causes no deadwe
45、ight loss.北大微观经济学ch16EquilibriumDeadweight Loss and Own-Price ElasticitiesuDeadweight loss due to a quantity tax rises as either market demand or market supply becomes more own-price elastic.uIf either e eD = 0 or e eS = 0 then the deadweight loss is zero.北大微观经济学ch16EquilibriumExamples of Equilibriu
46、m AnalysisuPrice ceilinguMinimum pricelAgricultural price controllMinimum wage北大微观经济学ch16EquilibriumpD(p), S(p)p*q*pmaxDABCEFqSPrice control CS=C-E PS=-C-FDWL=-E-F +waiting in lineqD北大微观经济学ch16EquilibriumpD(p), S(p)p*q*pmaxDABCEFqmaxPrice control with rationing CS=C-E PS=-C-FDWL=-E-F +corruption北大微观经济学ch16EquilibriumpD(p), S(p)p*q*psDABCEFqmaxPrice floor with acreage controlPayment=E+F+G CS=-B-E PS=B-F+paymentGovernment loss=paymentDWL=-E-FG北大微观经济学ch16EquilibriumMinimum WageuSingle sector single type of laboruCovered vs. uncovered sectoruSkilled vs. unskilled workers北大微观经济学ch16Equilibrium
