CHAPTER 3 OUTLINE 3.1 소비자의 선호 3.2 예산제약 3.3 소비자 선택 3.4 현시선호 3.5 한계효용과 소비자 선택 3.6 생계비지수

소비자 행동 ● 소비자행동 이론: 소비자가 만족(효용)을 그대화하기 위해 소득을 여러 재화와 서비스에 어떻게 배분하는가를 설명하는 이론 소비자행동이론의 3 단계 소비자 선호 예산제약 소비자 선택

소비자 선호 3.1 시장바스켓 ● 시장바스켓 (or 묶음) 하나 또는 그 이상의 재화들의 양의 집합(목록). TABLE 3.1 Alternative Market Baskets A 20 30 B 10 50 D 40 E G H Market Basket Units of Food Units of Clothing To explain the theory of consumer behavior, we will ask whether consumers prefer one market basket to another.

3.1 소비자 선호 S선호에 관한 기본적 가정 완전성(Completeness): 소비자는 모든 가능한 바스켓을 비교하여 순위를 정할 수 있다. For Baskets A and B, a consumer will prefer A to B, will prefer B to A, or will be indifferent between the two. By indifferent we mean that a person will be equally satisfied with either basket. 그러나 여기서 비용은 고려하지 않는다.

소비자 선호 3.1 선호에 대한 기본적 가정 전이성(Transitivity): 소비의 일관성을 위해 필요하다. Transitivity means that if a consumer prefers basket A to basket B and basket B to basket C, then the consumer also prefers A to C. Transitivity is normally regarded as necessary for consumer consistency. 다다익선(More is better than less): 재화는 좋은 것이라고 가정한다. Consequently, consumers always prefer more of any good to less. In addition, consumers are never satisfied or satiated; more is always better, even if just a little better. This assumption is made for pedagogic reasons; namely, it simplifies the graphical analysis. Of course, some goods, such as air pollution, may be undesirable, and consumers will always prefer less. 우리는 여기서는 “bads(나쁜 재화)”는 다루지 않는다.

3.1 소비자 선호 I무차별곡선 Figure 3.1 Describing Individual Preferences Because more of each good is preferred to less, we can compare market baskets in the shaded areas. Basket A is clearly preferred to basket G, while E is clearly preferred to A. However, A cannot be compared with B, D, or H without additional information.

소비자 선호 3.1 무차별곡선 ● 무차별곡선:한 소비자에게 같은 수준의 만족을 주는 모든 시장바스켓들(집합)을 나타내는 곡선. ● 무차별곡선:한 소비자에게 같은 수준의 만족을 주는 모든 시장바스켓들(집합)을 나타내는 곡선. Figure 3.2 An Indifference Curve The indifference curve U1 that passes through market basket A shows all baskets that give the consumer the same level of satisfaction as does market basket A; these include baskets B and D. Our consumer prefers basket E, which lies above U1, to A, but prefers A to H or G, which lie below U1.

소비자 선호 3.1 무차별지도 ● 무차별지도: 여러 개의 무차별곡선을 나타내는 그래프. ● 무차별지도: 여러 개의 무차별곡선을 나타내는 그래프. Figure 3.3 An Indifference Map An indifference map is a set of indifference curves that describes a person's preferences. Any market basket on indifference curve U3, such as basket A, is preferred to any basket on curve U2 (e.g., basket B), which in turn is preferred to any basket on U1, such as D.

3.1 소비자 선호 무차별곡선의 특성 Figure 3.4 무차별곡선들은 서로 교차하지 않음 If indifference curves U1 and U2 intersect, one of the assumptions of consumer theory is violated. According to this diagram, the consumer should be indifferent among market baskets A, B, and D. Yet B should be preferred to D because B has more of both goods.

3.1 소비자 선호 한계대체율 ● 한계대체율(MRS) 소비자가 어떤 재화 1단위를 추가적으로 얻기 위해 포기하려고 하는 다른 재화의 양. Figure 3.5 한계대체율 The magnitude of the slope of an indifference curve measures the consumer’s marginal rate of substitution (MRS) between two goods. In this figure, the MRS between clothing (C) and food (F) falls from 6 (between A and B) to 4 (between B and D) to 2 (between D and E) to 1 (between E and G). 볼록성(Convexity) MRS가 감소하는 것은 한계대채율체감의 법칙을 반영한다. 볼록한 모양을 갖는다.

소비자 선호 3.1 ●완전대체재: 한 재화의 다른 재화에 대한 한계대체율이 일정한 크기를 갖는 두 재화. 완전대체재와 완전보완재 ●완전대체재: 한 재화의 다른 재화에 대한 한계대체율이 일정한 크기를 갖는 두 재화. ●완전보완재: 한계대체율이 영이거나 무한대인 두 재화로 무차별곡선이 직각을 이룸. Bads ●나쁜 재화(bad): 소비자들이 저 적은 양을 갖기를 원하는 재화.

3.1 소비자 선호 완전대체재와 완전보완재 Figure 3.6 Perfect Substitutes and Perfect Complements In (a), Bob views orange juice and apple juice as perfect substitutes: He is always indifferent between a glass of one and a glass of the other. In (b), Jane views left shoes and right shoes as perfect complements: An additional left shoe gives her no extra satisfaction unless she also obtains the matching right shoe.

3.1 소비자 선호 Figure 3.7 자동차 특성에 대한 선호 Preferences for automobile attributes can be described by indifference curves. Each curve shows the combination of acceleration and interior space that give the same satisfaction. Owners of Ford Mustang coupes (a) are willing to give up considerable interior space for additional acceleration. The opposite is true for owners of Ford Explorers (b). They prefer interior space to acceleration.

소비자 선호 3.1 효용과 효용함수 ● 효용(utility): 소비자가 어떤 시장바스켓으로부터 얻는 만족수준을 나타내는 수치 ● 효용함수(utility function)각 시장바스켓의 효용의 크기를 부여하는 공식. Figure 3.8 Utility Functions and Indifference Curves A utility function can be represented by a set of indifference curves, each with a numerical indicator. This figure shows three indifference curves (with utility levels of 25, 50, and 100, respectively) associated with the utility function FC.

3.1 소비자 선호 서수적효용과 기수적 효용 ● 서수적 효용함수: 시장바스켓들이 가져다 주는 효용의 크기에 순위를 부여하는 함수. ● 기수적 효용함수:: 한 시장바스켓이 다른 시장바스켓에 비해 얼마나 더 선호되는지를 나타내는 함수. Figure 3.9 소득과 행복 A cross-country comparison shows that individuals living in countries with higher GDP per capita are on average happier than those living in countries with lower per-capita GDP.

예산제약 3.2 ●예산제약: 제한된 소득으로 인해 소비자가 직면하는 제약 예산선 ●예산선: 지출된 총 금액이 소득과 같게 되는 재화들의 모든 배합. (3.1) TABLE 3.2 Market Baskets and the Budget Line A 40 $80 B 20 30 D E 60 10 G 80 Market Basket Food (F) Clothing (C) Total Spending The table shows market baskets associated with the budget line F + 2C = $80

3.2 예산제약 예산선 Figure 3.10 A Budget Line A budget line describes the combinations of goods that can be purchased given the consumer’s income and the prices of the goods. Line AG (which passes through points B, D, and E) shows the budget associated with an income of $80, a price of food of PF = $1 per unit, and a price of clothing of PC = $2 per unit. The slope of the budget line (measured between points B and D) is −PF/PC = −10/20 = −1/2. (3.2)

3.2 예산제약 소득과 가격변화의 효과 Figure 3.11 Effects of a Change in Income on the Budget Line Income Changes A change in income (with prices unchanged) causes the budget line to shift parallel to the original line (L1). When the income of $80 (on L1) is increased to $160, the budget line shifts outward to L2. If the income falls to $40, the line shifts inward to L3.

3.2 예산제약 소득과 가격변화의 효과 Figure 3.12 Effects of a Change in Price on the Budget Line Price Changes A change in the price of one good (with income unchanged) causes the budget line to rotate about one intercept. When the price of food falls from $1.00 to $0.50, the budget line rotates outward from L1 to L2. However, when the price increases from $1.00 to $2.00, the line rotates inward from L1 to L3.

소비자 선택 3.3 두 조건: 시장바스켓이 예산선상에 있어야 함. 소비자에게 가장 큰 만족을 주는 시장바스켓이어야 함. Figure 3.13 소비자 만족의 극대화 A consumer maximizes satisfaction by choosing market basket A. At this point, the budget line and indifference curve U2 are tangent. No higher level of satisfaction (e.g., market basket D) can be attained. At A, the point of maximization, the MRS between the two goods equals the price ratio. At B, however, because the MRS [− (−10/10) = 1] is greater than the price ratio (1/2), satisfaction is not maximized.

소비자 선택 3.3 ●한계혜택: 어떤 재화를 추가적으로 1단위 더 소비함으로써 얻는 혜택(편익). 예산제약하에서 소비자 만족의 극대화 조건 (3.3) ●한계혜택: 어떤 재화를 추가적으로 1단위 더 소비함으로써 얻는 혜택(편익). ●한계비용: 어던 재화를 추가적으로 1단위 더 얻는데 드는 비용 In this instance, satisfaction is maximized when the marginal benefit—the benefit associated with the consumption of one additional unit of food—is equal to the marginal cost—the cost of the additional unit of food. The marginal benefit is measured by the MRS.

3.3 소비자 선택 Figure 3.14 Consumer Choice of Automobile Attributes The consumers in (a) are willing to trade off a considerable amount of interior space for some additional acceleration. Given a budget constraint, they will choose a car that emphasizes acceleration. The opposite is true for consumers in (b).

소비자 선택 3.3 ●귀퉁이 답:재화간의 한계대체율과 예산선의 기울기(상대가격)가 같지 않은 상황. 귀퉁이 답(Corner Solutions) ●귀퉁이 답:재화간의 한계대체율과 예산선의 기울기(상대가격)가 같지 않은 상황. Figure 3.15 A Corner Solution When the consumer’s marginal rate of substitution is not equal to the price ratio for all levels of consumption, a corner solution arises. The consumer maximizes satisfaction by consuming only one of the two goods. Given budget line AB, the highest level of satisfaction is achieved at B on indifference curve U1, where the MRS (of ice cream for frozen yogurt) is greater than the ratio of the price of ice cream to the price of frozen yogurt.

3.3 소비자의 선택 Figure 3.16 대학교육용 신탁기금 When given a college trust fund that must be spent on education, the student moves from A to B, a corner solution. If, however, the trust fund could be spent on other consumption as well as education, the student would be better off at C.

3.4 표출된 선호 I한 소비자가 어떤 시장바스켓보다 다른 시장바스켓을 선택하고, 선택된 시장바스켓이 선택되지 않은 시장바스켓보다 더 많은 지출을 요구하는 것이라면 이 소비자는 자신이 선택한 시장바스켓을 선호함에 틀림없다. Figure 3.17 Revealed Preference: Two Budget Lines If an individual facing budget line l1 chose market basket A rather than market basket B, A is revealed to be preferred to B. Likewise, the individual facing budget line l2 chooses market basket B, which is then revealed to be preferred to market basket D. Whereas A is preferred to all market baskets in the green-shaded area, all baskets in the pink-shaded area are preferred to A.

3.4 표출된 선호 Figure 3.18 Revealed Preference: Four Budget Lines Facing budget line l3 the individual chooses E, which is revealed to be preferred to A (because A could have been chosen). Likewise, facing line l4, the individual chooses G which is also revealed to be preferred to A. Whereas A is preferred to all market baskets in the green-shaded area, all market baskets in the pink-shaded area are preferred to A.

3.4 표출된 선호 Figure 3.19 Revealed Preference for Recreation When facing budget line l1, an individual chooses to use a health club for 10 hours per week at point A. When the fees are altered, she faces budget line l2. She is then made better off because market basket A can still be purchased, as can market basket B, which lies on a higher indifference curve.

3.5 한계효용과 소비자 선택 ●한계효용 (MU) : 어떤 재화를 추가적으로 1단위 더 소비할 때 얻는 추가적인 만족(효용)의 크기. ●한계효용체감:어떤 재 화의 소비량이 증가함에 따라 추가적인 소비량이 가져다 주는 추가적인 효용의 크기는 점점 작아진다는 원칙. (3.5) (3.6) (3.7) ●한계치 균등의 원칙:모든 재화에 지출되는 화폐 1단위에 대한 한계효용이 같을 때 소비자의 효용이 극대화되는 원칙.

3.5 한계효용과 소비자 선택 Figure 3.20 Marginal Utility and Happiness A comparison of mean levels of satisfaction with life across income classes in the United States shows that happiness increases with income, but at a diminishing rate.

3.5 한계효용과 소비자 선택 Figure 3.21 Inefficiency of Gasoline Rationing When a good is rationed, less is available than consumers would like to buy. Consumers may be worse off. Without gasoline rationing, up to 20,000 gallons of gasoline are available for consumption (at point B). The consumer chooses point C on indifference curve U2, consuming 5000 gallons of gasoline. However, with a limit of 2000 gallons of gasoline under rationing (at point E), the consumer moves to D on the lower indifference curve U1.

3.5 한계효용과 소비자 선택 Figure 3.22 Comparing Gasoline Rationing to the Free Market If the price of gasoline in a competitive market is $2.00 per gallon and the maximum consumption of gasoline is 10,000 gallons per year, the woman is better off under rationing (which holds the price at $1.00 per gallon), since she chooses the market basket at point F, which lies below indifference curve U1 (the level of utility achieved under rationing). However, she would prefer a free market if the competitive price were $1.50 per gallon, since she would select market basket G, which lies above indifference curve U1.

3.6 생계비지수 ●생계비지수: 대표적인 소비재와 서비스의 묶음을 구매하는데 드는 현재의 비용을 기준연도에 그 묶음을 구매하는데 드는 비용으로 나눈 비율 Ideal Cost-of-Living Index ●이상적 생계비지수:현재의 가격에서 어떤 수준의 효용을 달성하는데 드는 비용을 기준연도의 가격에서 같은 수준의 효용을 달성하는데 드는 비용으로 나눈 수치

생계비지수 3.6 이상적 생계비지수 TABLE 3.3 Ideal Cost-of-Living Index Price of books $20/book $100/book Number of books 15 6 Price of food $2.00/lb. $2.20/lb. Pounds of food 100 300 Expenditure $500 $1260 1995 (Sarah) 2005 (Rachel) Figure 3.23 Cost-of-Living Indexes The initial budget constraint facing Sarah in 1995 is given by line l1; her utility-maximizing combination of food and books is at point A on indifference curve U1. Rachel requires a budget sufficient to purchase the food-book consumption bundle given by point B on line l2 (and tangent to indifference curve U1).

생계비지수 3.6 이상적 생계비지수 TABLE 3.3 Ideal Cost-of-Living Index Price of books $20/book $100/book Number of books 15 6 Price of food $2.00/lb. $2.20/lb. Pounds of food 100 300 Expenditure $500 $1260 1995 (Sarah) 2005 (Rachel) Figure 3.23 Cost-of-Living Indexes A price index, which represents the cost of buying bundle A at current prices relative to the cost of bundle A at base-year prices, overstates the ideal cost-of-living index.

생계비지수 3.6 라스파이레스지수 (Laspeyres Index) ● Laspeyres price index :소비자가 기준연도에 선택한 재화와 서비스의 묶음을 현재가격으로 사는데 필요한 금액을 기준연도의 가격으로 사는데 필요한 금액으로 나눈 값 Comparing Ideal Cost-of-Living and Laspeyres Indexes The Laspeyres index overcompensates Rachel for the higher cost of living, and the Laspeyres cost-of-living index is, therefore, greater than the ideal cost-of-living index. 파쉐지수 ●파쉐(Paasche index) 현재연도에 선택한 재화와 서비스의 묶음을 현재가격으로 사는데 필요한 금액을 기준연도의 가격으로 사는데 필요한 금액으로 나눈 값. Comparing the Laspeyres and Paasche Indexes Just as the Laspeyres index will overstate the ideal cost of living, the Paasche will understate it because it assumes that the individual will buy the current-year bundle in the base period.

3.6 생계비지수 ●고정가중치 지수(fixed-weight index): 소비되는 재화와 서비스의 양이 공정된 것으로 하여 구한 생계비 지수. Price Indexes in the United States: Chain Weighting ●연쇄가중치 지수(chain-weighted price index) 재화와 서비스의 양의 변화를 반영하는 생계비지수. A commission chaired by Stanford University professor Michael Boskin concluded that the CPI overstated inflation by approximately 1.1 percentage points—a significant amount given the relatively low rate of inflation in the United States in recent years. Approximately 0.4 percentage points of the 1.1-percentage-point bias was due to the failure of the Laspeyres price index to account for changes in the current year mix of consumption of the products in the base-year bundle.