第8次課經(jīng)濟學(xué)競爭性壟斷

1、 2007 Thomson South-WesternMonopolistic Competition 壟斷競爭Imperfect competition refers to those market structures that fall between perfect competition and pure monopoly.不完全競爭是指處于完全競爭與純粹壟斷之間的那些市場結(jié)構(gòu).The Four Types of Market Structure四種市場結(jié)構(gòu)的類型 Tap water Cable TVMonopoly(Chapter 15) Novels MoviesMonopoli

2、sticCompetition(Chapter 17) Tennis balls Crude oilOligopoly(Chapter 16)Number of Firms?Perfect Wheat MilkCompetition(Chapter 14)Type of Products?IdenticalproductsDifferentiatedproductsOnefirmFewfirmsManyfirmsMonopolistic Competition 壟斷競爭Types of Imperfectly Competitive Markets 不完全競爭的市場類型Monopolistic

3、 Competition 壟斷競爭Many firms selling products that are similar but not identical.許多企業(yè)出售類似但是并不相同的產(chǎn)品Oligopoly 寡頭Only a few sellers, each offering a similar or identical product to the others.只有幾個賣者,每一賣者提供類似的或者相同的產(chǎn)品。Monopolistic Competition 壟斷競爭Markets that have some features of competition and some fea

4、tures of monopoly.具有競爭和壟斷的某些特征的市場Attributes of monopolistic competition:壟斷競爭的屬性：Many sellers 有許多賣者Product differentiation 產(chǎn)品差異化Free entry and exit 自由進入與退出Monopolistic Competition 壟斷競爭Many Sellers 有許多賣者There are many firms competing for the same group of customers.許多企業(yè)為爭奪同一批顧客而競爭Product examples incl

5、ude books, CDs, movies, computer games, restaurants, piano lessons, cookies, furniture, etc.產(chǎn)品的范例包括書籍、CD、電影、電腦游戲、飯店、鋼琴課、餅干、家具等。Monopolistic Competition 壟斷競爭Product Differentiation 產(chǎn)品差異化Each firm produces a product that is at least slightly different from those of other firms.每一企業(yè)生產(chǎn)一種產(chǎn)品，這種產(chǎn)品與其他企業(yè)生產(chǎn)的那

6、些產(chǎn)品至少有略微的不同。Rather than being a price taker, each firm faces a downward-sloping demand curve.與價格的接受者不一樣的是，每一企業(yè)面對的是向下傾斜的需求曲線。Monopolistic Competition 壟斷競爭Free Entry or Exit 自由進入與退出Firms can enter or exit the market without restriction.企業(yè)可以沒有限制地進入或退出市場The number of firms in the market adjusts until ec

7、onomic profits are zero.市場中的企業(yè)數(shù)量一直調(diào)整到利潤為零時COMPETITION WITH DIFFERENTIATED PRODUCTS 差異化產(chǎn)品的競爭The Monopolistically Competitive Firm in the Short Run 短期中的壟斷競爭企業(yè)Short-run economic profits encourage new firms to enter the market. This:短期的經(jīng)濟利潤鼓勵新的企業(yè)進入市場，這就Increases the number of products offered.增加了所提供的產(chǎn)品數(shù)

8、量Reduces demand faced by firms already in the market.減少了現(xiàn)有企業(yè)所面對的需求Incumbent firms demand curves shift to the left.企業(yè)的需求曲線向左移動Demand for the incumbent firms products fall, and their profits decline. 對于孵化期之企業(yè)的產(chǎn)品需求下降，并且他們的利潤下降。Figure 1 Monopolistic Competition in the Short Run圖1：短期中的壟斷競爭Quantity0PriceP

9、rofit-maximizingquantityPriceDemandMRATC(a) Firm Makes ProfitAveragetotal costProfitMCThe Monopolistically Competitive Firm in the Short Run 短期中的壟斷競爭企業(yè)Short-run economic losses encourage firms to exit the market. 短期經(jīng)濟虧損鼓勵企業(yè)退出市場Decreases the number of products offered.減少所提供的生產(chǎn)數(shù)量Increases demand faced

10、 by the remaining firms.留存企業(yè)所面臨的需求增加Shifts the remaining firms demand curves to the right.留存企業(yè)的需求曲線向右移動Increases the remaining firms profits.留存企業(yè)的利潤增加Figure 1 Monopolistic Competitors in the Short Run圖1：短期中的壟斷競爭企業(yè)DemandQuantity0PricePriceLoss-minimizingquantityAveragetotal cost(b) Firm Makes LossesM

11、RLossesATCMCThe Long-Run Equilibrium 長期均衡Firms will enter and exit until the firms are making exactly zero economic profits.企業(yè)將進入和退出，直到企業(yè)獲得的經(jīng)濟利潤為零。Figure 2 A Monopolistic Competitor in the Long Run圖2:長期中的壟斷競爭者QuantityPrice0DemandMRATCMCProfit-maximizingquantityP = ATCThe demand curve is tangent to t

12、he ATC curve.需求曲線與ATC相切And this tangency lies vertically above the intersection of MR and MC.并且這一相切垂直于MR與MC的相交點之上The Long-Run Equilibrium 長期均衡Two Characteristics 兩個特征As in a monopoly, price exceeds marginal cost.如同在壟斷中那樣,價格超過邊際成本.Profit maximization requires marginal revenue to equal marginal cost.

13、利潤最大化要求邊際收益等于邊際成本The downward-sloping demand curve makes marginal revenue less than price. 向下傾斜的需求曲線使得邊際收益低于價格As in a competitive market, price equals average total cost.如同在競爭性市場那樣，價格等于平均總成本。Free entry and exit drive economic profit to zero.自由進入與退出使經(jīng)濟利潤趨于零Monopolistic versus Perfect Competition壟斷對完全

14、競爭There are two noteworthy differences between monopolistic and perfect competition:在壟斷與不完全競爭之間存在著兩個值得注意的差異：Excess capacity 過剩的生產(chǎn)能力Markup over marginal cost 對邊際成本的加成Monopolistic versus Perfect Competition壟斷對完全競爭Excess Capacity 生產(chǎn)能力過剩There is no excess capacity in perfect competition in the long run.

15、在完全競爭中，長期內(nèi)不存在生產(chǎn)能力過剩。Free entry results in competitive firms producing at the point where average total cost is minimized, which is the efficient scale of the firm.自由進入使得競爭性企業(yè)在平均總成本最小化的那一點上生產(chǎn)，該點是該企業(yè)的有效規(guī)模。There is excess capacity in monopolistic competition in the long run.在壟斷競爭中，長期內(nèi)存在著生產(chǎn)能力過剩In monopo

16、listic competition, output is less than the efficient scale of perfect competition.在壟斷競爭中，產(chǎn)出低于不完全競爭的有效規(guī)模。Figure 3 Monopolistic versus Perfect Competition圖3：壟斷對不完全競爭Quantity0PriceDemand(a) Monopolistically Competitive FirmQuantity0PriceP = MCP = MR(demandcurve)(b) Perfectly Competitive FirmMCATCMCATC

17、MREfficientscalePQuantityproducedQuantity produced =Efficient scaleMonopolistic versus Perfect Competition壟斷對完全競爭Markup over Marginal Cost 對邊際成本的加成For a competitive firm, price equals marginal cost.對于競爭性企業(yè)來說，價格等于邊際成本。For a monopolistically competitive firm, price exceeds marginal cost.對于壟斷競爭企業(yè)來說，價格超

18、過邊際成本。Because price exceeds marginal cost, an extra unit sold at the posted price means more profit for the monopolistically competitive firm.因為價格超過邊際成本，在公布價格上多出售一個單位，就意味著壟斷競爭企業(yè)獲得更多的利潤。Figure 3 Monopolistic versus Perfect Competition圖3：壟斷對完全競爭Quantity0PriceDemand(a) Monopolistically Competitive Firm

19、Quantity0PriceP = MCP = MR(demandcurve)(b) Perfectly Competitive FirmMarkupMCATCMCATCMRMarginalcostPQuantityproducedQuantity producedFigure 3 Monopolistic versus Perfect Competition圖3：壟斷對完全競爭Quantity0PriceDemand(a) Monopolistically Competitive FirmQuantity0PriceP = MCP = MR(demandcurve)(b) Perfectly

20、 Competitive FirmMarkupExcess capacityMCATCMCATCMRMarginalcostEfficientscalePQuantityproducedQuantity produced =Efficient scaleMonopolistic Competition and the Welfare of Society壟斷競爭與社會福利Monopolistic competition does not have all the desirable properties of perfect competition.壟斷競爭并不具有完全競爭所具有的所有令人歡迎

21、的屬性。Monopolistic Competition and the Welfare of Society壟斷競爭與社會福利There is the normal deadweight loss of monopoly pricing in monopolistic competition caused by the markup of price over marginal cost.壟斷競爭中的壟斷定價存在著正常的無謂損失，這是由超過邊際成本的價格加成所引起的。However, the administrative burden of regulating the pricing of

22、 all firms that produce differentiated products would be overwhelming. 然而，對所有生產(chǎn)差異化產(chǎn)品的企業(yè)之定價進行規(guī)制的行政管理負擔(dān)將是巨大的。Monopolistic Competition and the Welfare of Society壟斷競爭與社會福利Another way in which monopolistic competition may be socially inefficient is that the number of firms in the market may not be the “i

23、deal” one. There may be too much or too little entry.另外一種方式（在此方式中壟斷競爭也許對社會來說是有效的）是，市場中企業(yè)的數(shù)量也許并非“理想的”數(shù)量，也許存在著過多或者過少的進入。Monopolistic Competition and the Welfare of Society壟斷競爭與社會福利Externalities of entry include: 進入的外部性包括Product-variety externalities. 生產(chǎn)多樣性的外部性Because consumers get some consumer surplu

24、s from the introduction of a new product, entry of a new firm conveys a positive externality on consumers.因為消費者從新產(chǎn)品的引進中獲得了某些消費者剩余， 新企業(yè)的進入產(chǎn)生了對消費者的正的外部性。Business-stealing externalities. 偷竊生意的外部性Because other firms lose customers and profits from the entry of a new competitor, entry of a new firm impos

25、es a negative externality on existing firms.因為其他企業(yè)由于新企業(yè)的進入而失去了顧客和利潤，新企業(yè)的進入對現(xiàn)有企業(yè)強加了負的外部性。ADVERTISING 廣告When firms sell differentiated products and charge prices above marginal cost, each firm has an incentive to advertise in order to attract more buyers to its particular product.當(dāng)企業(yè)出售差異化產(chǎn)品并且索取超過邊際成本的

26、價格時，每一企業(yè)具有做廣告的激勵，以便為其特定的產(chǎn)品吸引更多的買者。ADVERTISING 廣告Firms that sell highly differentiated consumer goods typically spend between 10 and 20 percent of revenue on advertising.出售高度差異化之消費品的企業(yè)，通常把收益的10%-20%花費在做廣告上。Overall, about 2 percent of total revenue, or over $200 billion a year, is spent on advertising

27、.總體上說，大約有總收入的2%，或者每年超過2000億美圓的支出，花費在做廣告上。The Debate over Advertising 有關(guān)廣告的爭議Critics of advertising argue that firms advertise in order to manipulate peoples tastes. 廣告的批評者爭論說，企業(yè)做廣告是為了操縱人們的口味或偏好。They also argue that it impedes competition by implying that products are more different than they truly a

28、re.他們還爭論說，通過宣揚產(chǎn)品的差異比它們實際存在的差異更大的隱含意思，廣告妨礙了競爭。The Debate over Advertising 有關(guān)廣告的爭議Defenders argue that advertising provides information to consumers捍衛(wèi)者爭辯說，廣告向消費者提供信息。They also argue that advertising increases competition by offering a greater variety of products and prices.他們還爭辯說，通過提供大量的產(chǎn)品種類與不同價格，廣告增加

29、了競爭。Advertising as a Signal of QualityThe willingness of a firm to spend advertising dollars can be a signal to consumers about the quality of the product being offered.企業(yè)花錢做廣告的意愿可以成為消費者有關(guān)提供產(chǎn)品之質(zhì)量的信號。Brand Names 商標(biāo)Critics argue that brand names cause consumers to perceive differences that do not real

30、ly exist.批評者們爭論說商標(biāo)引起消費者認知那些并非真正存在的差異。Brand Names 商標(biāo)Economists have argued that brand names may be a useful way for consumers to ensure that the goods they are buying are of high quality.經(jīng)濟學(xué)家爭論說，商標(biāo)也許是使消費者確認他們所購買的商品是高質(zhì)量產(chǎn)品的一種有益方式。providing information about quality.提供有關(guān)質(zhì)量的信息giving firms incentive to maintain high quality.向企業(yè)提供維持高質(zhì)量的激勵Table 1 Monopolistic Competition: Between Perfect Competition and Monopoly表1：壟斷競爭-在完全競爭與壟斷之間A monopolistically competitive market is characterized by three attributes: many firms, differentiated products, and free entry.壟斷競爭的市場特征可以通過三個屬性來認知：