CHAPTER 8 OUTLINE 8.1 완전경쟁시장 8.2 이윤극대화 8.3 한계수입,한계비용, 이윤극대화 8.1 완전경쟁시장 8.2 이윤극대화 8.3 한계수입,한계비용, 이윤극대화 8.4 단기에서의 생산량 8.5 경쟁기업의 단기공급곡선 8.6 단기시장공급곡선 8.7 장기에서의 생산량 8.8 산업의 장기공급곡선

8.1 완전경쟁시장 완전경쟁 모형의 세가지 가정: (1)가격 순응자 (2) 제품의 동질성 (3) 자유로운 진입과 퇴출. 각 개별기업은 전체시장의 매우 적은 량을 생산하므로 , 개병기업의 생산량에 대한 의사결정은 시장가격에 영향을 미치지 않음.. ● price taker Firm that has no influence over market price and thus takes the price as given. 제품의 동질성 한 시장에 있는 모든 기업의 제품이 서로 완전 대체적일 때 , 기업이 자기 제품의 가격을 다른 기업보다 높게 책정한다면 제품을 판매하지 못한다..

8.1 완전경쟁시장 어떤 경우에 시장은 매우 경쟁적인가? 자유로운 진입과 퇴출 ● free entry (or exit) :기업이 한 산업에 들어가거나 , 한 산업으로부터 나오는 것을 어렵게 하는 어떤 비용이 발생하지 않는 상태. 어떤 경우에 시장은 매우 경쟁적인가? 기업들은 명시적으로든 묵시적으로든 가격을 책정할 때 서로 담합할 수 있으므로 많은 수의 기업이 있다는 것만으로 어떤 산업이 완전경쟁에 가깝다고 하기에는 충분하지 않다. 반대로 시장에 소수의 기업이 존재한다고 해서 경쟁적 행위가 없음을 의미하지 않는다..

8.2 이윤극대화 기업들은 이윤을 극대화하는가? 다른 형태의 조직 미시경제학에서 이윤극대화의 가정은 기업의 행위를 비교적 정확하게 예측해주며 또한 분석이 불필요하게 복잡하지 않기 때문이다. 개인소유자에 의해서 운영되는 조그만 기업에서는 모든 의사결정시 이윤이 가장 중요하게 고려될 것이다. 그러나 대기업에서는 매일의 의사결정을 하는 경영자는 소유자(주주)와는 거의 접촉이 없다. 따라서 매출액의 극대화 등 다른 목표를 가질 수 있다. 그러나 어떤 경우든 기업이 이윤극대화를 도모하지 않고는 생존이 어렵다. 경쟁산업에서 생존하는 기업들은 장기이윤의 극대화를 그들의 가장 높은 우선순위로 하고 있다.. 다른 형태의 조직 ● 협동조합(cooperative) 회원들의 상호 이익을 위해 회원들에 의해 공동 소유되고 운영되는 기업이나 사람들의 연합체

8.2 이윤극대화 Nationwide, condos are a far more common than co-ops, outnumbering them by a factor of nearly 10 to 1. In this regard, New York City is very different from the rest of the nation—co-ops are more popular, and outnumber condos by a factor of about 4 to 1. What accounts for the relative popularity of housing cooperatives in New York City? Part of the answer is historical. Housing cooperatives are a much older form of organization in the U.S. The building restrictions in New York have long disappeared, and yet the conversion of apartments from co-ops to condos has been relatively slow. The typical condominium apartment is worth about 15.5 percent more than a equivalent apartment held in the form of a co-op. It appears that in New York, many owners have been willing to forgo substantial amounts of money in order to achieve non-monetary benefits.

8.3 한계수입, 한계비용, 그리고 이윤극대화 ● 이윤(profit) 총수입과 총비용의 차이. π(q) = R(q) − C(q) ● 한계수입 생산량이 한 단위 증가하는데 따른 총수입의 변화. Figure 8.1 단기에서 이윤극대화조건 A firm chooses output q*, so that profit, the difference AB between revenue R and cost C, is maximized. At that output, marginal revenue (the slope of the revenue curve) is equal to marginal cost (the slope of the cost curve). Δπ/Δq = ΔR/Δq − ΔC/Δq = 0 MR(q) = MC(q)

8.3 한계수입, 한계비용, 그리고 이윤극대화 경쟁기업의 수요와 한계수입 Figure 8.2 Demand Curve Faced by a Competitive Firm A competitive firm supplies only a small portion of the total output of all the firms in an industry. Therefore, the firm takes the market price of the product as given, choosing its output on the assumption that the price will be unaffected by the output choice. In (a) the demand curve facing the firm is perfectly elastic, even though the market demand curve in (b) is downward sloping.

8.3 한계수입, 한계비용, 그리고 이윤극대화 경쟁기업의 수요와 한계수입 경쟁시장에서 개별기업의 수요곡선은 평균수입곡선이자 한계수입곡선임. Profit Maximization by a Competitive Firm MC(q) = MR = P

8.4 단기에서의 생산량 경쟁기업의 단기에서의 이윤극대화 한계비용곡선이 증가하는 점에서 한계수입과 한계비용이 같아야 함.. 갱산량 결정원칙(Output Rule): I기업은 한계수입이 한계비용과 일치하는 생산량을 생산해야 한다..

8.4 단기에서의 생산량 경쟁기업의 단기이윤 Figure 8.3 양의 이윤을 갖는 경쟁기업 In the short run, the competitive firm maximizes its profit by choosing an output q* at which its marginal cost MC is equal to the price P (or marginal revenue MR) of its product. The profit of the firm is measured by the rectangle ABCD. Any change in output, whether lower at q1 or higher at q2, will lead to lower profit.

8.4 단기에서의 생산량 경쟁기업의 단기이윤 Figure 8.4 손실을 발생시키고 있는 경쟁기업 A competitive firm should shut down if price is below AVC. The firm may produce in the short run if price is greater than average variable cost. 조업중단 원칙(Shut-Down Rule): 이윤극대화 생산량에서 가격이 평균변동비용보다 낮은 경우에는 기업은 조업을 중단해야 한다..

8.4 단기에서의 생산량 How should the manager determine the plant’s profit maximizing output? Recall that the smelting plant’s short-run marginal cost of production depends on whether it is running two or three shifts per day. Figure 8.5 The Short-Run Output of an Aluminum Smelting Plant In the short run, the plant should produce 600 tons per day if price is above $1140 per ton but less than $1300 per ton. If price is greater than $1300 per ton, it should run an overtime shift and produce 900 tons per day. If price drops below $1140 per ton, the firm should stop producing, but it should probably stay in business because the price may rise in the future.

8.4 단기에서의 생산량 The application of the rule that marginal revenue should equal marginal cost depends on a manager’s ability to estimate marginal cost. To obtain useful measures of cost, managers should keep three guidelines in mind. First, except under limited circumstances, average variable cost should not be used as a substitute for marginal cost. Second, a single item on a firm’s accounting ledger may have two components, only one of which involves marginal cost. Third, all opportunity costs should be included in determining marginal cost.

8.5 경쟁기업의 단기공급곡선 기업의 공급곡선은 평균가변비용보다 큰 한계비용곡선의 부분이다. Figure 8.6 경쟁기업의 단기공급곡선 In the short run, the firm chooses its output so that marginal cost MC is equal to price as long as the firm covers its average variable cost. The short-run supply curve is given by the crosshatched portion of the marginal cost curve.

8.5 경쟁기업의 단기공급곡선 경쟁기업의 단기이윤 Figure 8.7 생산요소가격 변화에 대한 기업의 반응 When the marginal cost of production for a firm increases (from MC1 to MC2), the level of output that maximizes profit falls (from q1 to q2). The shaded area in the figure gives the total savings to the firm (or equivalently, the reduction in lost profit) associated with the reduction in output from q1 to q2.

8.5 경쟁기업의 단기공급곡선 Although plenty of crude oil is available, the amount that you refine depends on the capacity of the refinery and the cost of production. Figure 8.8 The Short-Run Production of Petroleum Products As the refinery shifts from one processing unit to another, the marginal cost of producing petroleum products from crude oil increases sharply at several levels of output. As a result, the output level can be insensitive to some changes in price but very sensitive to others.

8.6 단기시장공급곡선 Elasticity of Market Supply Es = (ΔQ/Q)/(ΔP/P) Figure 8.9 단기에서의 산업공급곡선 The short-run industry supply curve is the summation of the supply curves of the individual firms. Because the third firm has a lower average variable cost curve than the first two firms, the market supply curve S begins at price P1 and follows the marginal cost curve of the third firm MC3 until price equals P2, when there is a kink. For P2 and all prices above it, the industry quantity supplied is the sum of the quantities supplied by each of the three firms. Elasticity of Market Supply Es = (ΔQ/Q)/(ΔP/P)

8.6 단기시장공급곡선 Table 8.1 The World Copper Industry (2006) Annual Production (Thousand Metric Tons) Marginal Cost (Dollars Per Pound) Country Australia Canada Chile Indonesia Peru Poland Russia US Zambia Country 950 600 5,400 800 1,050 530 720 1,220 540 Country 1.15 1.30 0.80 0.90 0.85 1.20 0.65 0.75 Source for Annual Production Data: U.S. Geological Survey, Mineral Commodity Summaries, January 2007. http://minerals.usgs.gov/minerals/pubs/mcs/2007/mcs2007.pdf. Source for Marginal Cost Data: Charles River Associates’ Estimates.

8.6 단기시장공급곡선 Figure 8.10 The Short-Run World Supply of Copper The supply curve for world copper is obtained by summing the marginal cost curves for each of the major copper-producing countries. The supply curve slopes upward because the marginal cost of production ranges from a low of 65 cents in Russia to a high of $1.30 in Canada.

8.6 단기시장공급곡선 단기 생산자잉여 ● 생산자잉여 한 기업이 생산하는 재화의 시장가격과 그 재화의 한계비용간의 차이를 그 기업이 생산하는 모든 단위에 대해 합한 것. Figure 8.11 Producer Surplus for a Firm The producer surplus for a firm is measured by the yellow area below the market price and above the marginal cost curve, between outputs 0 and q*, the profit-maximizing output. Alternatively, it is equal to rectangle ABCD because the sum of all marginal costs up to q* is equal to the variable costs of producing q*.

8.6 단기시장공급곡선 Producer Surplus in the Short Run 생산자잉여와 이윤 Producer surplus = PS = R − VC Profit = π = R − VC − FC Figure 8.12 Producer Surplus for a Market The producer surplus for a market is the area below the market price and above the market supply curve, between 0 and output Q*.

8.7 장기에서의 생산량 장기이윤의 극대화 경쟁기업의 장기 이윤극대화 생산량은 장기한계비용과 가격이 일치하는 점에서 결정된다. Figure 8.13 Output Choice in the Long Run The firm maximizes its profit by choosing the output at which price equals long-run marginal cost LMC. In the diagram, the firm increases its profit from ABCD to EFGD by increasing its output in the long run. 경쟁기업의 장기 이윤극대화 생산량은 장기한계비용과 가격이 일치하는 점에서 결정된다.

8.7 장기에서의 생산량 장기경쟁균형 회게적 이윤과 경제적 이윤 π = R − wL − rK 영의 경제적 이윤 ● zero economic profit : 영의 경제적 이윤은 기업이 투자한 금액에 대해서 정상이윤을 얻고 있다는 것을 의미한다..

8.7 장기에서의 생산량 장기경쟁균형 진입과 퇴출 Figure 8.14 Long-Run Competitive Equilibrium Initially the long-run equilibrium price of a product is $40 per unit, shown in (b) as the intersection of demand curve D and supply curve S1. In (a) we see that firms earn positive profits because long-run average cost reaches a minimum of $30 (at q2). Positive profit encourages entry of new firms and causes a shift to the right in the supply curve to S2, as shown in (b). The long-run equilibrium occurs at a price of $30, as shown in (a), where each firm earns zero profit and there is no incentive to enter or exit the industry.

8.7 장기에서의 생산량 장기경쟁균형 진입과 퇴출 진입과 퇴출이 자유로운 시장에서 기업은 양의 장기이윤을 벌 수 있을 때 시장에 진입하고 장기손실이 직면하는 경우 시장에서 퇴출한다. ● 장기경쟁균형: 해당 산업에 있는 모든 기업은 이윤을 극대화하고 있으며, 어떤 기업도 해당산업에 진입하거나 해당산업에서 퇴출하려는 인센티브를 갖지 않으며, 가격은 공급량과 수요량을 일치시키는 수준에서 결정된다. 장기경쟁균형의 세가지 조건: 해당산업에 있는 모든 기업이 이윤을 극대화하고 있다.. 2. 모든 기업이 영의 경제적 이윤을 얻고 있기 때문에 어떤 기업도 해당산업에서 진입하거나 퇴출하려는 인센티브를 갖지 않는다.. 3. 해당 재화의 가격은 생산자에 의해서 공급되는 공급량과 소비자에 의해서 수요되는 수요량을 일치시키는 수준으로 결정된다..

8.7 장기에서의 생산량 장기경쟁균형 동일한 비용을 갖는 기업들 To see why all the conditions for long-run equilibrium must hold, assume that all firms have identical costs. Now consider what happens if too many firms enter the industry in response to an opportunity for profit. The industry supply curve will shift further to the right, and price will fall. 다른 비용을 갖는 기업들 Now suppose that all firms in the industry do not have identical cost curves. The distinction between accounting profit and economic profit is important here. If a patent is profitable, other firms in the industry will pay to use it. The increased value of a patent thus represents an opportunity cost to the firm that holds it.

8.7 장기에서의 생산량 장기경쟁균형 Economic Rent 토지의 기회비용 There are other instances in which firms earning positive accounting profit may be earning zero economic profit. Suppose, for example, that a clothing store happens to be located near a large shopping center. The additional flow of customers can substantially increase the store’s accounting profit because the cost of the land is based on its historical cost. Economic Rent ● 경제적 지대 : 기업들이 한 생산요소에 대해 지불하고자 하는 금액에서 그 생산요소를 구입하기 위해 지불해야 하는 최소금액을 차감한 것.

8.7 장기에서의 생산량 장기에서의 생산자 잉여 I장기에 경쟁시장에서 한 기업이 생산물을 판매함으로써 얻는 생산자잉여는 모든 희소한 생산요소로부터 얻는 경제적 지대로 구성된다..

8.7 장기에서의 생산량 장기에서의 생산자 잉여 Figure 8.15 Firms Earn Zero Profit in Long-Run Equilibrium In long-run equilibrium, all firms earn zero economic profit. In (a), a baseball team in a moderate-sized city sells enough tickets so that price ($7) is equal to marginal and average cost. In (b), the demand is greater, so a $10 price can be charged. The team increases sales to the point at which the average cost of production plus the average economic rent is equal to the ticket price. When the opportunity cost associated with owning the franchise is taken into account, the team earns zero economic profit.

8.8 산업의 장기공급곡선 비용불변산업 ● constant-cost industry : 장기공급곡선이 수평선인 산업. Figure 8.16 Long-Run Supply in a Constant-Cost Industry In (b), the long-run supply curve in a constant-cost industry is a horizontal line SL. When demand increases, initially causing a price rise (represented by a move from point A to point C), the firm initially increases its output from q1 to q2, as shown in (a). But the entry of new firms causes a shift to the right in industry supply. Because input prices are unaffected by the increased output of the industry, entry occurs until the original price is obtained (at point B in (b)). The long-run supply curve for a constant-cost industry is, therefore, a horizontal line at a price that is equal to the long-run minimum average cost of production.

8.8 산업의 장기공급곡선 비용증가산업 ● increasing-cost industry :장기공급곡선이 우상향하는 산업. Figure 8.17 Long-Run Supply in an Increasing-Cost Industry In (b), the long-run supply curve in an increasing-cost industry is an upward-sloping curve SL. When demand increases, initially causing a price rise, the firms increase their output from q1 to q2 in (a). In that case, the entry of new firms causes a shift to the right in supply from S1 to S2. Because input prices increase as a result, the new long-run equilibrium occurs at a higher price than the initial equilibrium. In an increasing-cost industry, the long-run industry supply curve is upward sloping.

8.8 산업의 장기공급곡선 비용감소산업 ● decreasing-cost industry :장기공급곡선이 우하향 는 산업. You have been introduced to industries that have constant, increasing, and decreasing long-run costs. We saw that the supply of coffee is extremely elastic in the long run. The reason is that land for growing coffee is widely available and the costs of planting and caring for trees remains constant as the volume grows. Thus, coffee is a constant-cost industry. The oil industry is an increasing-cost industry because there is a limited availability of easily accessible, large-volume oil fields. Finally, a decreasing-cost industry. In the automobile industry, certain cost advantages arise because inputs can be acquired more cheaply as the volume of production increases.

8.8 산업의 장기공급곡선 세금의 효과 Figure 8.18 경쟁기업의 생산물에 대한 세금효과 An output tax raises the firm’s marginal cost curve by the amount of the tax. The firm will reduce its output to the point at which the marginal cost plus the tax is equal to the price of the product.

8.8 산업의 장기공급곡선 세금의 효과 Figure 8.19 생산물에 대한 세금이 산업의 생산량에 미치는 효과 An output tax placed on all firms in a competitive market shifts the supply curve for the industry upward by the amount of the tax. This shift raises the market price of the product and lowers the total output of the industry.

8.8 산업의 장기공급곡선 공급의 장기탄력성 Owner-occupied and rental housing provide interesting examples of the range of possible supply elasticities. If the price of housing services were to rise in one area of the country, the quantity of services could increase substantially. Even when elasticity of supply is measured within urban areas, where land costs rise as the demand for housing services increases, the long-run elasticity of supply is still likely to be large because land costs make up only about one-quarter of total housing costs. The market for rental housing is different, however. The construction of rental housing is often restricted by local zoning laws.