CHAPTER 2 OUTLINE 2.1 공급과 수요 2.2 시장기능 2.3 시장균형의 변화 2.4 공급과 수요의 탄력성 2.5 단기 대 장기탄력성 2.6 시장조건의 변화효과에 대한 이해와 예측 2.7 정부개입- 가격통제의 효과

공급과 수요의 기초 수요-공급모형은 다양한 흥미롭고 중요한 문제에 적용할 수 있는 미시경제학의 기본적 이면서도 강력한 분석도구이다. 약간의 예를 들면: 세계여건의 변화가 시장가격과 생산에 어떠한 효과를 미치는지 이해하고 예측함. 정부의 가격통제, 최저임금, 가격지지, 그리고 생산인센티브제도 등의 효과를 평가함. 세금, 보조금, 관세, 수입쿼터 등이 소비자와 생산자에게 어떤 영향을 미치는지 결정함.

공급과 수요 2.1 공급곡선 ● 공급곡선 :생산자가 판매하고자 하는 한 재화의 수량과 그 재화의 가격간의 관계를 나타낸다. ● 공급곡선 :생산자가 판매하고자 하는 한 재화의 수량과 그 재화의 가격간의 관계를 나타낸다. Figure 2.1 공급곡선 S로 표시된 공급곡선은 재화의 가격이 변함에 따라 생산자들이 판매하고자 하는 수량이 달라진다는 것을 보여준다. 공급곡선은 우상향한다. 다른 조건이 일정하다면 가격이 상승할 수록 생산자들은 더 많은 량을 생산하여 판매하고자 한다. 생산비용이 하락한다면 기업들은 같은 양을 낮은 가격에 팔 수 있거나 , 같은 가격에서 더 많은 양을 팔 수 있다. 이는 공급곡선을 오른쪽으로 이동시킨다.

공급과 수요 2.1 공급곡선 공급에 영향을 미치는 다른 변수들 공급곡선은 가격(P)과 공급량(QS)간의 관계를 나타낸다. 우리는 이 관계를 하나의 방정식을 쓸 수 있다. QS = QS(P) 공급에 영향을 미치는 다른 변수들 - 생산비용: 임금, 이자율, 원재료 가격 등. 생산비용이 감소하면 모든 시장가격에서 생산량은 증가한다. 따라서 공급곡선 전체가 오른쪽으로 이동된다.. 공급곡선의 이동을 ‘ 공급의 변화’ 라고 표현하고, 가격의 변화에 따른 공급곡선상의 이동을 ‘공급량’의 변화라고 한다

2.1 공급과 수요 수요곡선 ● 수요곡선: 한 재화의 가격과 소비자들이 사려고 하는 그 재화의 양 간의 관계를 나타냄 수요량(QD )과 가격(P )간의 관계는 하나의 방정식으로 나타낼 수 있음. QD = QD(P)

2.1 공급과 수요 수요곡선 Figure 2.2 수요곡선 D로 표시된 수요곡선은 소비자들에 의한 한 재화의 소비량이 그 것의 가격에 의존함을 나타냄. 수요곡선은 수요곡선은 우하향한다. 다른 것들이 일정하다면 소비자들은 한 재화의 가격이 하락할 수록 그 재화를 더 많이 사려고 할 것이다. 수요량은 또한 소득,기후, 다른 재화들의 가격 같은 변수들에도 의존한다. 대부분의 상품에서 소득이 올라갈 때 수요량은 증가한다.. 더 높은 소득수준은 수요곡선을 오른쪽으로 이동시킨다.(from D to D’).

공급과 수요 2.1 수요곡선 수요곡선의 이동 수요곡선의 이동 시장가격이 P1, 으로 고정되어 있을 때 소비자들의 소득이 증가하면 수요량은 Q1 에서 Q2,로 증가할 것이다. 그 결과 전체 수요곡선이 오른 쪽으로 이동한다.. 수요곡선의 이동 ● 대체재:한 재화의 가격상승이 다른 재화의 수요량의 증가를 가져오는 재화. ● 보완재: 한 재화의 가격상승이 다른 재화의 수요량 감소를 가져오는 재화.

시장기능 2.2 P0 의 가격과 Q0. 수량에서 시장은 청산된다. Figure 2.3 공급과 수요 더 높은 가격 P1, 에서는 공급과잉이 발생하여 가격을 하락하고 고 더 낮은 가격 P2, 에서는 공급부족이 발생하여 가격이 상승한다..

시장기능 2.2 균형 ● 균형(혹은 시장청산)가격 : 수요량과 공급량을 일치시키는 가격. ● 균형(혹은 시장청산)가격 : 수요량과 공급량을 일치시키는 가격. ● 시장기능(market mechanism ) 자유로운 시장에서 수요량과 공급량이 일치될 때까지 가격이 변하는 경향. ● 공급과인(surplus) 공급량이 수요량보다 더 큰 상황- 초과공급. ● 공급부족: 수요량이 공급량보다 큰 상황-초과수요.

시장기능 2.2 수요공급모형은 언제 사용하는가? -시장이 대체적으로 경쟁시장에 가까울 경우이다 . -시장이 대체적으로 경쟁시장에 가까울 경우이다 . 이것은 구매자와 판매자가 모두 시장지배력( market power, 즉 개별적으로 시장가격에 영향을 줄 수 있는 힘)이 없다고 생각함.

2.3 시장균형의 변화 Figure 2.4 New Equilibrium Following Shift in Supply When the supply curve shifts to the right, the market clears at a lower price P3 and a larger quantity Q3.

시장균형의 변화 2.3 When the demand curve shifts to the right, Figure 2.5 New Equilibrium Following Shift in Demand When the demand curve shifts to the right, the market clears at a higher price P3 and a larger quantity Q3.

2.3 시장균형의 변화 Figure 2.6 New Equilibrium Following Shifts in Supply and Demand Supply and demand curves shift over time as market conditions change. In this example, rightward shifts of the supply and demand curves lead to a slightly higher price and a much larger quantity. In general, changes in price and quantity depend on the amount by which each curve shifts and the shape of each curve.

2.3 시장균형의 변화 From 1970 to 2007, the real (constant-dollar) price of eggs fell by 49 percent, while the real price of a college education rose by 105 percent. The mechanization of poultry farms sharply reduced the cost of producing eggs, shifting the supply curve downward. The demand curve for eggs shifted to the left as a more health-conscious population tended to avoid eggs. As for college, increases in the costs of equipping and maintaining modern classrooms, laboratories, and libraries, along with increases in faculty salaries, pushed the supply curve up. The demand curve shifted to the right as a larger percentage of a growing number of high school graduates decided that a college education was essential.

2.3 시장균형의 변화 Figure 2.7 (a) Market for Eggs The supply curve for eggs shifted downward as production costs fell; the demand curve shifted to the left as consumer preferences changed. As a result, the real price of eggs fell sharply and egg consumption rose.

2.3 시장균형의 변화 Figure 2.7 (b) Market for College Education The supply curve for a college education shifted up as the costs of equipment, maintenance, and staffing rose. The demand curve shifted to the right as a growing number of high school graduates desired a college education. As a result, both price and enrollments rose sharply.

2.3 시장균형의 변화 Over the past two decades, the wages of skilled high-income workers have grown substantially, while the wages of unskilled low-income workers have fallen slightly. From 1978 to 2005, people in the top 20 percent of the income distribution experienced an increase in their average real (inflation-adjusted) pretax household income of 50 percent, while those in the bottom 20 percent saw their average real pretax income increase by only 6 percent. While the supply of unskilled workers—people with limited educations—has grown substantially, the demand for them has risen only slightly. On the other hand, while the supply of skilled workers—e.g., engineers, scientists, managers, and economists—has grown slowly, the demand has risen dramatically, pushing wages up.

2.3 시장균형의 변화 Figure 2.8 Consumption and the Price of Copper Although annual consumption of copper has increased about a hundredfold, the real (inflation-adjusted) price has not changed much.

2.3 시장균형의 변화 Figure 2.9 Long-Run Movements of Supply and Demand for Mineral Resources Although demand for most resources has increased dramatically over the past century, prices have fallen or risen only slightly in real (inflation-adjusted) terms because cost reductions have shifted the supply curve to the right just as dramatically.

2.3 시장균형의 변화 Figure 2.10 Supply and Demand for New York City Office Space Following 9/11 the supply curve shifted to the left, but the demand curve also shifted to the left, so that the average rental price fell.

공급과 수요의 가격탄력성 2.4 수요의 가격탄력성 탄력성: 한 변수가 1 퍼센트 증가할 때 다른 변수가 변하는 퍼센트. 탄력성: 한 변수가 1 퍼센트 증가할 때 다른 변수가 변하는 퍼센트. 수요의 가격탄력성 수요의 가격탄력성: 어떤 재화의 가격이 1퍼센트 증가할 때 그로 인하여 변하는 수요량의 퍼센트. (2.1)

공급과 수요의 탄력성 2.4 직선의 수요곡선 직선수요곡선: 수요곡선이 직선임. Figure 2.11 Linear Demand Curve The price elasticity of demand depends not only on the slope of the demand curve but also on the price and quantity. The elasticity, therefore, varies along the curve as price and quantity change. Slope is constant for this linear demand curve. Near the top, because price is high and quantity is small, the elasticity is large in magnitude. The elasticity becomes smaller as we move down the curve.

2.4 공급과 수요의 가격탄력성 직선수요곡선 Figure 2.12 (a) Infinitely Elastic Demand (a) For a horizontal demand curve, ΔQ/ΔP is infinite. Because a tiny change in price leads to an enormous change in demand, the elasticity of demand is infinite. infinitely elastic demand Principle that consumers will buy as much of a good as they can get at a single price, but for any higher price the quantity demanded drops to zero, while for any lower price the quantity demanded increases without limit.

2.4 공급과 수요의 탄력성 직선 수요곡선 Figure 2.12 (b) Completely Inelastic Demand (b) For a vertical demand curve, ΔQ/ΔP is zero. Because the quantity demanded is the same no matter what the price, the elasticity of demand is zero. completely inelastic demand Principle that consumers will buy a fixed quantity of a good regardless of its price.

공급과 수요의 탄력성 2.4 수요의 다른 탄력성들 공급의 탄력성 수요의 소득탄력성: 소득이 1퍼센트 증가할 때 수요량이 변하는 퍼센트. (2.2) 수요의 교차가격탄력성:다른 재화의 가격이 1퍼센트 상승할 때 한 재화의 수요량이 변하는 퍼센트r. (2.3) 공급의 탄력성 공급의 가격탄력성: 가격이 1퍼센트 변할 때 공급량이 변하는 퍼센트.

공급과 수요의 탄력성 2.4 점탄력성과 호탄력성 수요의 호탄력성 수요의 점 탄력성: 수요곡선상의 특정한 점에서의 탄력성. 수요의 점 탄력성: 수요곡선상의 특정한 점에서의 탄력성. 수요의 호탄력성 수요의 호탄력성: 수요곡선상의 어떤 범위에 걸친 가격변화에 대해 계산된 가격탄력성. (2.4)

2.4 공급과 수요의 탄력성 During recent decades, changes in the wheat market had major implications for both American farmers and U.S. agricultural policy. To understand what happened, let’s examine the behavior of supply and demand beginning in 1981. By setting the quantity supplied equal to the quantity demanded, we can determine the market-clearing price of wheat for 1981:

공급과 수요의 탄력성 2.4 Substituting into the supply curve equation, we get We use the demand curve to find the price elasticity of demand: Thus demand is inelastic. We can likewise calculate the price elasticity of supply: Because these supply and demand curves are linear, the price elasticities will vary as we move along the curves.

2.5 단기탄력성과 장기탄력성 수요 Figure 2.13 (a) Gasoline: Short-Run and Long-Run Demand Curves (a) In the short run, an increase in price has only a small effect on the quantity of gasoline demanded. Motorists may drive less, but they will not change the kinds of cars they are driving overnight. In the longer run, however, because they will shift to smaller and more fuel-efficient cars, the effect of the price increase will be larger. Demand, therefore, is more elastic in the long run than in the short run.

2.5 단기탄력성과 장기탄력성 수요 수요와 내구성 Figure 2.13 (b) Automobiles: Short-Run and Long-Run Demand Curves (b) The opposite is true for automobile demand. If price increases, consumers initially defer buying new cars; thus annual quantity demanded falls sharply. In the longer run, however, old cars wear out and must be replaced; thus annual quantity demanded picks up. Demand, therefore, is less elastic in the long run than in the short run.

단기탄력성과 장기탄력성 2.5 수요 소득탄력성 I소득탄력성도 단기와 장기가 다르다. 대부분의 재화와 서비스– 식품, 음료수, 연료,오락 등에서 장기탄력성이 장기탄력성이 더 크다. 내구재의 경우는 이와 반대이다. 수요의 단기소득탄력성이 장기탄력성 보다 더 크다..

단기탄력성과 장기탄력성 2.5 Demand Cyclical Industries cyclical industries Industries in which sales tend to magnify cyclical changes in gross domestic product and national income. Figure 2.14 GDP and Investment in Durable Equipment Annual growth rates are compared for GDP and investment in durable equipment. Because the short-run GDP elasticity of demand is larger than the long-run elasticity for long-lived capital equipment, changes in investment in equipment magnify changes in GDP. Thus capital goods industries are considered “cyclical.”

단기탄력성과 장기탄력성 2.5 Demand Cyclical Industries Figure 2.15 Consumption of Durables versus Nondurables Annual growth rates are compared for GDP, consumer expenditures on durable goods (automobiles, appliances, furniture, etc.), and consumer expenditures on nondurable goods (food, clothing, services, etc.). Because the stock of durables is large compared with annual demand, short-run demand elasticities are larger than long-run elasticities. Like capital equipment, industries that produce consumer durables are “cyclical” (i.e., changes in GDP are magnified). This is not true for producers of nondurables.

단기탄력성과 장기탄력성 2.5 Demand TABLE 2.1 Demand for Gasoline Number of Years Allowed to Pass Following a Price or Income Change Elasticity 1 2 3 5 10 Price −0.2 −0.3 −0.4 −0.5 −0.8 Income 0.2 0.4 0.5 0.6 1.0 TABLE 2.2 Demand for Automobiles Number of Years Allowed to Pass Following a Price or Income Change Elasticity 1 2 3 5 10 Price −1.2 −0.9 −0.8 −0.6 −0.4 Income 3.0 2.3 1.9 1.4 1.0

2.5 단가탄력성과 장기탄력성 공급 공급과 내구성 Figure 2.16 Copper: Short-Run and Long-Run Supply Curves Like that of most goods, the supply of primary copper, shown in part (a), is more elastic in the long run. If price increases, firms would like to produce more but are limited by capacity constraints in the short run. In the longer run, they can add to capacity and produce more.

단가탄력성과 장기탄력성 2.5 공급y 공급과 내구성 Figure 2.16 Copper: Short-Run and Long-Run Supply Curves Part (b) shows supply curves for secondary copper. If the price increases, there is a greater incentive to convert scrap copper into new supply. Initially, therefore, secondary supply (i.e., supply from scrap) increases sharply. But later, as the stock of scrap falls, secondary supply contracts. Secondary supply is therefore less elastic in the long run than in the short run. Table 2.3 Supply of Copper Price Elasticity of: Short-Run Long-Run Primary supply 0.20 1.60 Secondary supply 0.43 0.31 Total supply 0.25 1.50

2.5 단기탄력성과 장기탄력성 Figure 2.17 Price of Brazilian Coffee When droughts or freezes damage Brazil’s coffee trees, the price of coffee can soar. The price usually falls again after a few years, as demand and supply adjust.

2.5 단가탄력성과 장기탄력성 Figure 2.18 Supply and Demand for Coffee (a) A freeze or drought in Brazil causes the supply curve to shift to the left. In the short run, supply is completely inelastic; only a fixed number of coffee beans can be harvested. Demand is also relatively inelastic; consumers change their habits only slowly. As a result, the initial effect of the freeze is a sharp increase in price, from P0 to P1.

2.5 단기탄력성과 장기탄력성 Figure 2.18 Supply and Demand for Coffee (b) In the intermediate run, supply and demand are both more elastic; thus price falls part of the way back, to P2.

2.5 단가탄력성과 장기탄력성 Figure 2.18 Supply and Demand for Coffee (c) In the long run, supply is extremely elastic; because new coffee trees will have had time to mature, the effect of the freeze will have disappeared. Price returns to P0.

2.6 시장상황의 변화에 대한 이해와 예측 Figure 2.19 Fitting Linear Supply and Demand Curves to Data Linear supply and demand curves provide a convenient tool for analysis. Given data for the equilibrium price and quantity P* and Q*, as well as estimates of the elasticities of demand and supply ED and ES, we can calculate the parameters c and d for the supply curve and a and b for the demand curve. (In the case drawn here, c < 0.) The curves can then be used to analyze the behavior of the market quantitatively.

시장상황의 변화에 대한 이해와 예측 2.6 Demand: Q = a − bP Supply: Q = c + dP Step 1: E = (P/Q)(ΔQ/ΔP) Demand: ED = −b(P*/Q*) (2.6a) Supply: ES = d(P*/Q*) (2.6b) Step 2: a = Q* + bP* Q = a − bP + fI (2.7)

2.6 시장상황의 변화에 대한 이해와 예측 After reaching a level of about $1.00 per pound in 1980, the price of copper fell sharply to about 60 cents per pound in 1986. Worldwide recessions in 1980 and 1982 contributed to the decline of copper prices. Why did the price increase sharply in 2005–2007? First, the demand for copper from China and other Asian countries began increasing dramatically. Second, because prices had dropped so much from 1996 through 2003, producers closed unprofitable mines and cut production. What would a decline in demand do to the price of copper? To find out, we can use linear supply and demand curves.

2.6 시장상황의 변화에 대한 이해와 예측 Figure 2.20 Copper Prices, 1965–2007 Copper prices are shown in both nominal (no adjustment for inflation) and real (inflation-adjusted) terms. In real terms, copper prices declined steeply from the early 1970s through the mid-1980s as demand fell. In 1988–1990, copper prices rose in response to supply disruptions caused by strikes in Peru and Canada but later fell after the strikes ended. Prices declined during the 1996–2002 period but then increased sharply during 2005–2007.

2.6 시장상황의 변화에 대한 이해와 예측 Figure 2.21 Copper Supply and Demand The shift in the demand curve corresponding to a 20-percent decline in demand leads to a 10.5-percent decline in price.

시장상황의 변화에 대한 이해와 예측 2.6 Since the early 1970s, the world oil market has been buffeted by the OPEC cartel and by political turmoil in the Persian Gulf. Figure 2.22 Price of Crude Oil The OPEC cartel and political events caused the price of oil to rise sharply at times. It later fell as supply and demand adjusted.

2.6 시장상황의 변화에 대한 이해와 예측 Because this example is set in 2005–2007, all prices are measured in 2005 dollars. Here are some rough figures: 2005–7 world price = $50 per barrel World demand and total supply = 34 billion barrels per year (bb/yr) OPEC supply = 14 bb/yr Competitive (non-OPEC) supply = 20 bb/yr The following table gives price elasticity estimates for oil supply and demand: Short Run Long Run World demand: Competitive supply: -0.05 -0.40 0.10 0.40

2.6 시장상황의 변화에 대한 이해와 예측 Figure 2.23 Impact of Saudi Production Cut The total supply (ST) is the sum of competitive (non-OPEC) supply (SC) and the 14 bb/yr of OPEC supply. Part (a) shows the short-run supply and demand curves. If Saudi Arabia stops producing, the supply curve will shift to the left by 3 bb/yr. In the short-run, price will increase sharply. Part (b) shows long-run curves. In the long run, because demand and competitive supply are much more elastic, the impact on price will be much smaller.

2.7 정부간섭의 효과- 가격통제 Figure 2.24 Effects of Price Controls Without price controls, the market clears at the equilibrium price and quantity P0 and Q0. If price is regulated to be no higher than Pmax, the quantity supplied falls to Q1, the quantity demanded increases to Q2, and a shortage develops.

2.7 정부간섭의 효과- 가격통제 Figure 2.25 Price of Natural Gas Natural gas prices rose sharply after 2000, as did the prices of oil and other fuels.

정부간섭의 효과- 가격통제 2.7 Supply: Q = 15.90 + 0.72PG + 0.05PO The (free-market) wholesale price of natural gas was $6.40 per mcf (thousand cubic feet); Production and consumption of gas were 23 Tcf (trillion cubic feet); The average price of crude oil (which affects the supply and demand for natural gas) was about $50 per barrel. Supply: Q = 15.90 + 0.72PG + 0.05PO Demand: Q = 0.02 – 0.18PG + 0.69PO Substitute $3.00 for PG in both the supply and demand equations (keeping the price of oil, PO, fixed at $50). You should find that the supply equation gives a quantity supplied of 20.6 Tcf and the demand equation a quantity demanded of 29.1 Tcf. Therefore, these price controls would create an excess demand of 29.1 − 20.6 = 8.5 Tcf.