andinternationaltrade(發(fā)展經(jīng)濟(jì)學(xué)-廈門大學(xué),陳濤-文庫吧資料
2025-01-14 19:06本頁面
【正文】 is total cost divided by output. – Marginal Cost (MC) is the amount it costs the firm to produce one extra unit. The Theory of Imperfect Competition 12 – When average costs decline in output, marginal cost is always less than average cost. – Suppose the costs of a firm, C, take the form: C = F + c x Q (63) – This is a linear cost function. – The fixed cost in a linear cost function gives rise to economies of scale, because the larger the firm’s output, the less is fixed cost per unit. –The firm’s average costs is given by: AC = C/Q = F/Q + c (64) The Theory of Imperfect Competition 13 Figure 62: Average Versus Marginal Cost The Theory of Imperfect Competition Average cost Marginal cost 1 2 0 3 4 5 6 2 4 6 8 10 12 14 16 18 20 22 24 Cost per unit Output 14 ? Monopolistic Competition ? Oligopoly – Internal economies generate an oligopoly market structure. – There are several firms, each of which is large enough to affect prices, but none with an uncontested monopoly. – Strategic interactions among oligopolists have bee important. – Each firm decides its own actions, taking into account how that decision might influence its rival’s actions. The Theory of Imperfect Competition 15 ? Monopolistic petition – A special case of oligopoly – Two key assumptions are made to get around the problem of interdependence: – Each firm is assumed to be able to differentiate its product from its rivals. – Each firm is assumed to take the prices charged by its rivals as given. The Theory of Imperfect Competition 16 ? Are there any monopolistically petitive industries in the real world? – Some industries may be reasonable approximations (., the automobile industry in Europe) – The main appeal of the monopolistic petition model is not its realism, but its simplicity. The Theory of Imperfect Competition 17 ? Assumptions of the Model – Imagine an industry consisting of a number of firms producing differentiated products. – We expect a firm: – To sell more the larger the total demand for its industry’s product and the higher the prices charged by its rivals – To sell less the greater the number of firms in the industry and the higher its own price The Theory of Imperfect Competition 18 where: –Q is the firm’s sales –S is the total sales of the industry –n is the number of firms in the industry –b is a constant term representing the responsiveness of a firm’s sales to its price –P is the price charged by the firm itself –A particular equation for the demand facing a firm that has these properties is: Q = S x [1/n – b x (P – P)] (65) The Theory of Imperfect Competition –P is the average price charged by its petitors 19 ? Market Equilibrium – All firms in this industry are symmetric – The demand function and cost function are identical for all firms. – The method for determining the number of firms and the average price charged involves three steps: – We derive a relationship between the number of firms and the average cost of a typical firm. – We derive a relationship between the number of firms and the price each firm charges. – We derive the equilibrium number of firms and the average price that firms charge. The Theory of Imperfect Competition 20 ? The number of firms and average cost – How do the average costs depend on the number of firms in the industry? The Theory of Imperfect Competition – Under symmetry, P = P, equation (65) tells us that Q = S/n but equation (64) shows us that the average cost depends inversely on a firm’s output. – We conclude that average cost depends on the size of the market and the number of firms in the industry: AC = F/Q + c = n x F/S
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