第四讲 企业行为与产业组织

PART IV 企业行为与产业组织（FIRM BEHA VIOR AND THE ORGANIZATION OF INDUSTRY）●生产与成本●完全竞争●完全垄断●垄断竞争●寡头The Firm’s Objective—“Maximize their profit”Profit = Total Revenue – Total Cost= TR – TC•Total Revenue•The amount a firm receives for the sale of its output.•Total Cost•The market value of the inputs a firm uses in production.一、生产与成本（Production and Cost）（一）生产理论（Production Theory）1.生产函数（Production Function）The production function shows the relationship between quantity of inputs used to make a good and the quantity of output of that good.Q=ƒ（X1，X2，X3…）Q=ƒ（L,K）2.短期与长期（Short Run and Long Run）•Short Run• A period in which firms can adjust production by changing variable factors such as materials andlabor, but cannot change fixed factors such ascapital.•Long Run• A period sufficiently long so that all factors including capital can be adjusted.3.短期的生产（Production in the Short Run）Q=ƒ（L,K）= ƒ(L)总产量（Total Product）The Total product is the total amount of output produced by factors of production.TP L= Q=ƒ（L,K）= ƒ(L)平均产量（Average Product）The Average product is the output per unit of the variable factor.AP L=TP L/L边际产量（Marginal Product）The Marginal product is the increase in output that arises from an additional unit of the variable input.MP L=△TP L/△L =d TP L/d L边际收益（产量）递减规律（Law of diminishing returns）The marginal product of an input will decline as the amount of that input increases, holding all other inputs constant.生产的三阶段分析：•厂商在短期生产时，会将生产稳定在第二阶段。

3.长期的生产（Production in the Long Run）Q=ƒ（L,K）等产量线（Equal-Production Curve）The equal-production curve depicts the alternative input combinations that produce the same level of output.等产量线的特点：•Higher equal-production curves are represent higher level of output.•Equal-production curves are downward sloping.•Equal-production curves do not cross.•Equal-production curves are bowed inward边际技术替代率（MRTS LK）•It is the rate at which a producer is willing to trade one factor of production for another.•It is the amount of one factor of production that a producer requires as compensation to give up one unit of another.MRTS LK= -ΔK/ΔLMRTS LK= -dK/dL等成本线（Equal-Cost Line）The equal-cost line represents the same level of expenditure by a firm for various combinations of two inputs, when prices of the two inputs are fixed.rK+wL=C最小成本的要素组合（The Least-Cost Equilibrium）MRTS LK=w/rMP L/MP K=w/rMP L/w=MP K/r生产扩展线（Expansion Path）（二）成本理论（The Cost of Production）1.经济成本与经济利润(Economic Cost & Economic Profit) Economic cost is all opportunity cost of making firm’s output of goods and services.Economic Cost = Explicit Cost + Implicit Cost= Accounting Cost + Implicit Cost Economic Profit = TR – TC= TR – Explicit Cost – Implicit Cost= Accounting Profit – Implicit Cost= Excess Profit2.短期成本（Costs in the short run）短期总成本（STC）可变成本（Variable Cost）：costs which do vary with output 固定成本（Fixed Cost）:cost which do not change with output 短期平均总成本（SAC）= STC/Q平均可变成本（Average Variable Cost）= VC/Q平均固定成本（Average Fixed Cost）= FC/Q短期边际成本（SMC）= △STC/△Q = dSTC/dQ= △VC/△Q = dVC/dQSMC rises with the amount of output produced. This reflects the property of diminishing MP.3.长期成本（Costs in the Long Run）长期总成本（LTC）长期平均成本（LAC）长期边际成本（LMC）规模经济（Economies of Scale）:the property whereby long-run average total cost falls as the quantity of output increases.规模报酬不变（Constant Return to Scale）: the property whereby long-run average total cost stays the same as the quantity of output changes.规模不经济（Diseconomies of Scale）:the property whereby long-run average total cost rises as the quantity of output increases.二、完全竞争（Perfect Competition）1.单个厂商的需求曲线（A Competitive Firm’s DemandCurve）2.竞争性厂商的收益曲线总收益（TR）平均收益（AR）=TR/Q边际收益（MR）= △TR/△Q = dTR/dQA competitive firm’s MR: MR=P3.利润最大化（产量）条件（Profit Maximization Condition）MR = MCA competitive firm’s profit maximization condition:P = MC4. 短期的供给抉择(Supply in the Short Run)Profit Maximization Condition : P = SMCThe competitive firm’s short-run supply curve is the portion of its marginal cost curve that lies above average variable cost.沉没成本（Sunk Cost）: a cost when it has already been committed and cannot be recovered.•Once a cost is sunk, it is no longer an opportunity cost.•We can see fixed cost as sunk cost in the short run.5.生产者剩余（Producer Surplus）Producer Surplus is the amount a seller is paid for a good minus the seller’s cost.6.长期供给抉择（Supply Decision in the Long Run）Profit Maximization Condition : P = LMC7. 对竞争性市场均衡的评价（Evaluating the Competitive Market Equilibrium）Total surplus = Consumer surplus – Producer surplus = (Value to buyers – Amount paid by buyers)-(Amount received by sellers – Costs of sellers)=Value to buyers –Costs of sellers三、完全垄断（Monopoly）1.垄断厂商的需求曲线（A Monopolist’s Demand Curve）2.垄断厂商的收益曲线总收益（TR）平均收益（AR）=TR/Q边际收益（MR）= △TR/△Q = dTR/dQA Monopolist’s MR: MR<P3.利润最大化（产量）条件（Profit Maximization Condition）MR = MC4. 短期的供给抉择(Supply in the Short Run)Profit Maximization Condition: MR = SMC5.长期供给抉择（Supply Decision in the Long Run）Profit Maximization Condition: MR = LMC垄断厂商没有供给曲线6.垄断的福利损失——无谓损失（The Welfare Cost of Monopoly：Deadweight Loss）●From the standpoint of consumer, monopoly isundesirable.●From the standpoint of producer, monopoly is desirable.●From the standpoint of society as a whole, monopoly isundesirable.7.价格歧视（Price Discrimination）Price discrimination is the business practice of selling the same good at different prices to different customers.Three Lessons about Price Discrimination:●Price discrimination is a rational strategy for aprofit-maximizing monopolist.●Price discrimination requires the ability to separatecustomers according to their willingness to pay.●Price discrimination can raise economic welfare.四、垄断竞争（Monopolistic Competition）1.垄断竞争厂商的需求曲线（A Monopolistic Competitor Demand Curve）2. 垄断竞争厂商的收益曲线（A Monopolistic Competitor Revenue Curve）总收益（TR）平均收益（AR）=TR/Q边际收益（MR）= △TR/△Q = dTR/dQMR<P3.利润最大化（产量）条件（Profit Maximization Condition）MR = MC4. 短期的供给抉择(Supply in the Short Run)Profit Maximization Condition: MR = SMC5.长期供给抉择（Supply Decision in the Long Run）Profit Maximization Condition: MR = LMC=LAC6.垄断竞争与完全竞争（Monopolistic versus Perfect Competition）There are two noteworthy differences between monopolistic and perfect competition—excess capacity and markup.•Excess Capacity•There is no excess capacity in perfect competition in the long run.•Free entry results in competitive firms producing at the point where average total cost is minimized,which is the efficient scale of the firm.•There is excess capacity in monopolistic competition in the long run.•In monopolistic competition, output is less than the efficient scale of perfect competition.•Markup Over Marginal Cost•For a competitive firm, price equals marginal cost.•For a monopolistically competitive firm, priceexceeds marginal cost.•Because price exceeds marginal cost, an extra unit sold at the posted price means more profit for themonopolistically competitive firm.7.垄断竞争与社会福利（Monopolistic Competition and the Welfare of Society）•Monopolistic competition does not have all of the desirable properties of perfect competition.•There is a standard deadweight loss of monopoly caused by the markup of price over marginal cost.•The number of firms can be too large or too small.思考：要对这种市场中的企业施加管制吗？Figure 1 The Four Types of Market StructureNumber of Firms?Competition Competition五、寡头（Oligopoly）1、双头（A Duopoly Example）A duopoly is an oligopoly with only two members. It is the simplest type of oligopoly.Product：WaterWithout Cost：MC=0The Demand Schedule for Water•Price and Quantity Supplied•The price of water in a perfectly competitive market would be driven to where the marginalcost is zero:•P = MC = $0•Q = 120 gallons•The price and quantity in a monopoly market would be where total profit is maximized:•P = $60•Q = 60 gallonsSo what outcome then could be expected from duopolists?•The duopolists may agree on a monopoly outcome.•Collusion•An agreement among firms in a marketabout quantities to produce or prices tocharge.•Cartel• A group of firms acting in unison.•Although oligopolists would like to form cartels and earn monopoly profits, often that is not possible.Antitrust laws prohibit explicit agreements among oligopolists as a matter of public policy.•Possible outcome if oligopoly firms pursue their ownself-interests:•Joint output is greater than the monopoly quantity but less than the competitive industryquantity.•Market prices are lower than monopoly price but greater than competitive price.•Total profits are less than the monopoly profit.2、纳什均衡（Nash Equilibrium）A Nash equilibrium is a situation in which economic actors interacting with one another each choose their best strategy given the strategies that all the others have chosen.3、博弈论与合作经济学（Game Theory and the Economics of Cooperation）•Game theory is the study of how people behave in strategic situations.•Strategic decisions are those in which each person, in deciding what actions to take, must consider how others might respond to that action.囚徒困境（P risoners’ Dilemma）•The priso ners’ dilemma provides insight into the difficulty in maintaining cooperation.•Often people (firms) fail to cooperate with one anothereven when cooperation would make them better off.占优策略：The dominant strategy is the best strategy for a player to follow regardless of the strategies chosen by the other players.• Cooperation is difficult to maintain, because cooperation is not in the best interest of the individual player.Confess。