【文章內(nèi)容簡介】 同質(zhì)商品的市場組織 ? 壟斷競爭市場的特征 （ 1）企業(yè)數(shù)量多但規(guī)模相對比較小 （ 2）產(chǎn)品相似又彼此差別 與完全競爭市場的差別所在，因而需求曲線向下傾斜 （ 3）企業(yè)進(jìn)出不受限制 與完全壟斷市場的差別所在，資源可以在行業(yè)間轉(zhuǎn)移 （ 4）眾多小的購買者 ? 壟斷競爭市場舉例 牙膏、洗發(fā)水、成都小吃店、鞋店、加油站 產(chǎn)品差異來自于位置、材料、做工和品牌等方面的不同 Key Implications ? Since products are differentiated, each firm faces a downward sloping demand curve。 firms have limited market power. 與完全壟斷類似 ? Free entry and exit, so firms will earn zero profits in the long run. 與完全競爭類似 Managing a Monopolistically Competitive Firm ? Market power permits you to price above marginal cost, just like a monopolist. ? How much you sell depends on the price you set, just like a monopolist. But … ? The presence of other brands in the market makes the demand for your brand more elastic than if you were a monopolist. ? You have limited market power. 壟斷競爭下的短期均衡 D q 0 pE mrE SMC SAC E dE P,C,R qE 短期均衡滿足： AR=AVC。MR=MC。否則廠商停產(chǎn) MR Long Run Adjustments? ? In the absence of free entry, no adjustments occur. ? If the industry is truly monopolistically petitive, there is free entry. – In this case other “greedy capitalists” enter, and their new brands steal market share. – This reduces the demand for your product until profits are ultimately zero. 壟斷競爭下的長期均衡 D q 0 pE LMC LAC E P,C,R qE MR 只要存在短期超額利潤，就有投資者進(jìn)入；隨著新企業(yè)的進(jìn)入， 替代品數(shù)量將增加，代表性企業(yè)面臨的需求曲線將向左下方移動。 隨著需求曲線的移動，超額利潤將降低，直至消失，此時，企業(yè) 停止進(jìn)出產(chǎn)業(yè)的行動，達(dá)到長期穩(wěn)定狀態(tài)。 D0 D1 $ AC MC D MR Q* P* Quantity of Brand X MR1 D1 Entry P1 Q1 Long Run Equilibrium (P = AC, so zero profits) Graphically 壟斷競爭下的長期均衡 （續(xù)） D q 0 pE LMC LAC E P,C,R qE MR （ 1）由于廠商可以自由進(jìn)入，壟斷競爭長期均衡滿足： LAC=AR=P， MC=MR （ 2）壟斷競爭的效率低于完全競爭（均衡價格高、均衡產(chǎn)量低），因?yàn)榫鈺r p≠M(fèi)C, 同時生產(chǎn)沒有推進(jìn)到平均成本最低點(diǎn) （ 3）壟斷競爭的效率高于完全壟斷 （ 4）壟斷競爭帶來了產(chǎn)品差異化，更好地滿足了消費(fèi)者；同時有利于技術(shù)進(jìn)步 Monopolistic Competition The Good (To Consumers) – Product Variety The Bad (To Society) – P MC – Excess capacity ? Unexploited economies of scale The Ugly (To Managers) – Zero Profits 壟斷競爭的決策舉例 “DogsGoneAway（狗去矣）”公司是芝加哥專門為寵物提供葬禮服務(wù)的公司。在芝加哥，寵物葬禮服務(wù)行業(yè)屬于壟斷競爭行業(yè)。 該公司經(jīng)理估計該企業(yè)面臨的需求方程為 p = , 而該公司的長期總成本函數(shù)為 : TC = 400Q 20Q2 +Q3 問： 該公司的長期均衡價格和產(chǎn)量各是多少？它將獲得多少利潤？此時，壟斷競爭的長期均衡條件是否得到滿足？ 壟斷競爭企業(yè)前景如何 ? 如何延遲零經(jīng)濟(jì)利潤的最終結(jié)局？ parison Maximizing Profits: A Synthesizing Example ? C(Q) = 125 + 4Q2 ? Determine the profitmaximizing output and price, and discuss its implications, if – You are a price taker and other firms charge $40 per unit。 – You are a monopolist and the inverse demand for your product is P = 100 Q。 – You are a monopolistically petitive firm and the inverse demand for your brand is P = 100 Q Marginal Cost ? C(Q) = 125 + 4Q2, ? So MC = 8Q ? This is independent of market structure Price Taker ? MR = P = $40 ? Set MR = MC ? 40 = 8Q ? Q = 5 units ? Cost of producing 5 units ? C(Q) = 125 + 4Q2 = 125 + 100 = 225 ? Revenues: ? PQ = (40)(5) = 200 ? Maximum profits of $25 ? Implications: Expect exit in the longrun Monopoly/Monopolistic Competition ? MR = 100 2Q (since P = 100 Q) ? Set MR = MC, or 100 2Q = 8Q – Optimal output: Q = 10 – Optimal price: P = 100 (10) = 90 – Maximal profits: ? PQ C(Q) = (90)(10) (125 + 4(100)) = 375 ? Implications – Monopolist will not face entry (unless patent or other entry barriers are eliminated) – Monopolistically petitive firm should expect other firms to clone, so profits will decline over time 寡頭壟斷 Oligopoly ? 在完全競爭、完全壟斷、壟斷競爭三種市場環(huán)境中，企業(yè)決策始終遵循著 SCP邏輯：即市場結(jié)構(gòu)決定企業(yè)行為和企業(yè)績效 Market Structure – Number of firms, size, etc. Conduct – Pricing, advertising, Ramp。D, etc. Performance – Profitability, consumer surplus, social welfare. ? 而在有些市場環(huán)境下，企業(yè)決策機(jī)制似乎難以固定描述。這些市場上，只有幾家企業(yè)，卻生產(chǎn)大部分或者全部市場產(chǎn)量，一家企業(yè)的產(chǎn)量或價格策略不僅給自己，而且給市場其它企業(yè)的銷量帶來顯著影響。這種環(huán)境下，企業(yè)經(jīng)理人的決策具有以下特點(diǎn)： 經(jīng)理們知道自己的決策會影響到對手的銷售情況和利潤水平 經(jīng)理們做出決策后，對手會對這些決策作出反應(yīng) 經(jīng)理們的銷售和利潤狀況依賴于對手的反應(yīng) 但是，經(jīng)理們并不確知對手實(shí)際上將如何反應(yīng) 在這種環(huán)境下，經(jīng)理人的成功在于學(xué)會如何預(yù)期市場中其它競爭對手的行動和反應(yīng)，從而作出利潤最大化的決策 寡頭的管理決策 ? 定義 某一產(chǎn)業(yè)只存在少數(shù)幾個賣者（通常少于 10個）的市場組織形式。 ? 分類 純寡頭： 生產(chǎn)同質(zhì)產(chǎn)品（如鋼鐵、水泥） 差別寡頭：生產(chǎn)異質(zhì)產(chǎn)品（如汽車、電腦） ? 特征 所有寡頭都具備市場力 寡頭之間行為不獨(dú)立 ，一家將對另一家的行為產(chǎn)生反應(yīng)（既可能競爭，也可能合作） 每個寡頭對市場都有舉足輕重的影響 ? 寡頭市場舉例 麥當(dāng)勞和 KFC 同一城市中的銀行業(yè)、電視臺、報紙 附近的電影院 北大西門的烤肉攤 An Example ? You and another firm sell differentiated products ? How does the quantity demanded for your product change when you change your price? P Q D1 P0 Q0 D2 (Rival matches your price change) (Rival holds its price constant) D Demand if Rivals Match Price Reductions but not Price Increases Key Insight ? The effect of a price reduction on the quantity demanded of your product depends upon whether your rivals respond by cutting their prices too! ?