新增11范中級微觀摘要

1、Chapter 1 1Chapter 1The MarketThis chapter was written so I would have something to talk about on the firstday of class. I wanted to gives an idea of what economics was all about,and what my lectures would be like, and yet not have anything that was reallycritical for the course. (At Michigan,s are

2、still shoparound on thefirst day, and a good number of them wont necessarily be at the lecture.)I chose to discuss a housing market since it gives a way to describe a numberof economic ideas in very simple language and gives a good guide to what liesahead. In this chapter I was deliberately looking

3、for surprising resultsanalytic insights that wouldnt arise from “just thinking” about a problem. The two most surprising results that I presented are the condominium example and the tax example in Section 1.6. It is worth emphasizing in class just why these results are true, and how they illustrate

4、the power of economic m ing.It also makes sense to describe their limitations. Suppose that every con- dominium conversion involved knocking out the walls and creating two apart- ments. Then what would happen to the price of apartments? Suppose that the condominiums attracted suburbanites who wouldn

5、t otherwise consider renting an apartment. In each of these cases, the price of remaining apartments would rise when condominium conversion took place.The point of a simple economic mof the sort considered here is to focus our thoughts on what the relevant effects are, not to come to a once-and-for-

6、all about the urban housing market. The real insight that is offered bythese examples is that you have to consider both the supply and the demand side of the apartment market when you analyze the impact of this particular policy.The only concept that thes seem to have trouble with in this chapteris

7、the idea of Pareto efficiency. I usually talk about the idea a little more than is in the book and rephrase it a few times. But then I tell them not to worryabout it too much, since well look at it in greatlater in the course.The workbook problems here are pretty straightforward. The biggest problem

8、is getting thes to draw the true (discontinuous) demand curve, as inFigure 1.1, rather than just to sketdownward-slocurve as in Figure1.2. This is a good time to emphasize to thes that when they are givennumbers describing a curve, they have to use the numbersthey cant just sketch in any old shape.2

9、 Chapter HighlightsThe MarketA. Example of an economic m the market for apartments1. ms are simplifications of reality2. for example, assume all apartments are identical3. some areto the university, others are far away4. price of outer-ring apartments is exogenous determined outside the m5. price of

10、 inner-ring apartments is endogenous determined within the mB. Two principles of economics1. optimization principle people choose actions that are in their interest2. equilibrium principle peopleions must eventually be consistent with each otherC. Constructing the demand curve1. line up the people b

11、y willingness-to-pay. See Figure 1.1.2. for large numbers of people, this is essentially a smooth curve as in Figure 1.2.D. Supply curve1. depends on time frame2. but well look at the short run when supply of apartments is fixed.E. Equilibrium1. when demand equals supply2. price that clears the mark

12、etF. Comparative statics1. how does equilibrium adjust when economic conditions change?2. “comparative” compare two equilibria3. “statics” only look at equilibria, not at adjustment4. example increase in supply lowers price; see Figure 1.5.5. example create condos which are purchased by renters; no

13、effect on price; see Figure 1.6.G. Other ways to allocate apartments1. discriminating monopolist2. ordinary monopolist3. rent controlH. Comparing different institutions1. need a criterion to compaow efficient these different allocation methods are.2. an allocation is Pareto efficient if there is no

14、way to make some group of people better off without making someone else worse off.3. if something is not Pareto efficient, then there is some way to make some people better off without making someone else worse off.4. if something is not Pareto efficient, then there is some kind of “waste” in the sy

15、stem.I. Checking efficiency of different methods1. market efficient2. discriminating monopolist efficient3. ordinary monopolist not efficient4. rent control not efficientChapter 1 3J. Equilibrium in long run1. supply will change2. can examine efficiency in this context as well4 Chapter HighlightsCha

16、pter 2Budget ConstraintMost of the material here is pretty straightforward. Drive home the formula for the slope of the budget line, emphasizing the derivation on page 23. Try some different notation to make sure that they see the idea of the budget line, and dont just memorize the formulas. In the

17、workbook, we use a number of different choices of notation for precisely this reason. It is also worth pointing out that the slope of a line depends on the (arbitrary) choice of which variable is plotted on the vertical axis. It is surprising how often confusion arises on this point.s sometimes have

18、 problems with the idea of a numeraire good. They understand the algebra, but they dont understand when it would be used. One nice example is in foreign currency exchange. If you have English pounds and American dollars, then you can measure the total wealth that you have in either dollars or pounds

19、 by choosing one or the other of the two goods as numeraire.In the workbook,s sometimes get thrown in exercises where one ofthe goods has a negative price, so the budget line has a positive slope. Thiscomes from trying to memorize formulas and figures rather than thinking aboutthe problem. This is a

20、 good exercise to go over in order to warn the dangers of rote learning!s aboutBudget ConstraintA. Consumer theory: consumers choose the best bundles of goods they can afford.1. this is virtually the entire theory in a nutshell2. but this theory has many surprising consequencesB. Two parts to theory

21、1. “can afford” budget constraint2. “best” according to consumers preferencesChapter 2 5C. What do we want to do with the theory?1. test it see if it is adequate to describe consumer behavior2. predict how behavior changes as economic environment changes3. use observed behavior to estimate underlyin

22、g valuesa) cost-benefit analysisb) predicting impact of some policyD. Consumption bundle1. (x1, x2) how much of each good is consumed2. (p1, p2) prices of the two goods3. m money the consumer has to spend4. budget constraint: p1x1 + p2x2 m5. all (x1, x2) that satisfy this constraint make up the budg

23、et set of the consumer. See Figure 2.1.E. Two goods1. theory works with more than two goods, but cant draw pictures.2. often think of good 2 (say) as a composite good, representing money to spend on other goods.3. budget constraint becomes p1x1 + x2 m.4. money spent on good 1 (p1x1) plus the money s

24、pent on good 2 (x2) has to be less than or equal to the amount available (m).F. Budget line1. p1x1 + p2x2 = m2. also written as x2 = m/p2 (p1/p2)x1.3. budget line has slope of p1/p2 and vertical intercept of m/p2.4. set x1 = 0 to find vertical intercept (m/p2); set x2 = 0 to find horizontal intercep

25、t (m/p1).5. slope of budget line measures opportucost of good 1 how much ofgood 2 you must give up in order to consume more of good 1.G. Changes in budget line1. increasing m makes parallel shift out. See Figure 2.2.2. increasing p1 makes budget line steeper. See Figure 2.3.3. increasing p2 makes bu

26、dget line flatter4. just see how intercepts change5. multiplying all prices by t is just like dividing income by t6. multiplying all prices and income by t doesnt change budget linea) “a perfectly balanced inflation doesnt change consumption possibili- ties”H. The numeraire1. can arbitrarily assign

27、one price a value of 1 and measure other price relative to that2. useful when measuring relative prices; e.g., English pounds per dollar, 1987 dollars versus 1974 dollars, etc.I. Taxes, subsidies, and rationing1. quty tax tax levied on units bought: p1 + t2. value tax tax levied on dollars spent: p1

28、 + p1. Also known as ad valorem tax3. subsidies opposite of a taxa) p1 sb) (1 )p16 Chapter Highlights4. lump sum tax or subsidy amount of tax or subsidy is independent of the consumers choices. Also called a head tax or a poll tax5. rationing cant consume more than a certain amount of some goodJ. Ex

29、ample food stamps1. before 1979 was an ad valorem subsidy on fooda) paid a certain amount of money to get food stamps which were worth more than they costb) some rationing component could only buy aum amount offood stamps2. after 1979 got a straight lump-sum grant of food coupons. Not the same as a

30、pure lump-sum grant since could only spend the coupons on food.Chapter 3 7Chapter 3PreferencesThis chapter is more abstract and therefore needs somewhat more motivation than the previous chapters. It might be a good idea to talk about relations in general before introducing the particular idea of pr

31、eference relations. Try the relations of “taller,” and “heavier,” and “taller and heavier.” Point out that “taller and heavier” isnt a complete relation, while the other two are. Thisgeneral discussion can motivate teral idea of preference relations.Make sure that thes learn the specific examples of

32、 preferences suchas perfect substitutes, perfect complements, etc. They will use these examples many, many times in the next few weeks!When describing the ideas of perfect substitutes, emphasize that the defining characteristic is that the slope of the indifference curves is constant, not that itis

33、1. In the text, I always stick with the case where the slope is 1, but inthe workbook, we often treat teral case. The same warning goes with theperfect complements case. I work out the symmetric case in the text and try toget thes to do the asymmetric case in the workbook.The definition of the margi

34、nal rate of substitution is fraught with “signconfusion.” Should the MRS be defined as a negative or a positive number? Ivechosen to give the MRS its natural sign in the book, but I warn thes thatmany economists tend to speak of the MRS in terms of absolute value. Example: diminishing marginal rate

35、of substitution refers to a situation where the absolute value of the MRS decreases as we move along an indifference curve. The actual value of the MRS (a negative number) is increasing in this movement!s often begin to have problems with the workbook exercises here.The first confusion they have is

36、that they get mixed up about the idea that indifference curves measure the directions where preferences are constant, and instead draw lines that indicate the directions that preferences are increasing. The second problem that they have is in knowing when to draw just arbitrary curves that qualitati

37、vely depict some behavior or other, and when to draw exact shapes.Try asking yours to draw their indifference curves between five dollarbills and one dollar bills. Offer to trade with them based on what they draw. In addition to getting them to think, this is a good way to supplement your faculty sa

38、lary.8 Chapter HighlightsPreferencesA. Preferences are relationships between bundles.1. if a consumer would choose bundle (x1, x2) when (y1, y2) is available, thenit is natural to say that bundle (x1, x2) is preferred to (y1, y2) by thisconsumer.2. preferences have to do with the entire bundle of go

39、ods, not with individual goods.B. Notation1. (x1, x2) (y1, y2) means the x-bundle is strictly preferred to the y-bundle2. (x1, x2) (y1, y2) means that the x-bundle is regarded as indifferent tothe y-bundle3. (x1, x2) (y1, y2) means the x-bundle is atleast as good as (preferredto or indifferent to) t

40、he y-bundleC. Assumptions about preferences1. complete any two bundles can be compared2. reflexive any bundle is at least as good as itself3. transitive if X Y and Y Z, then X Za) transitivity necessary for theory of optimal choiceD. Indifference curves1. graph the set of bundles that are indifferen

41、t to some bundle. See Figure 3.1.2. indifference curves are like contour lines on a map3. note that indifference curves describing two distinct levels of preference cannot cross. See Figure 3.2.a) proof use transitivityE. Examples of preferences1. perfect substitutes. Figure 3.3.a) red pencils and b

42、lue pencils; pints and quartsb) constant rate of trade-off between the two goods2. perfect complements. Figure 3.4.a) always consumed togetherb) right shoes and left shoes; coffee and cream3. bads. Figure 3.5.4. neutrals. Figure 3.6.5. satiation or bliss point Figure 3.7.F. Well-behaved preferences1

43、. monotonicity more of either good is bettera) implies indifference curves have negative slope. Figure 3.9.2. convexity averages are preferred to extremes. Figure 3.10.a) slope gets flatter as you move further to rightb) example of non-convex preferencesG. Marginal rate of substitution1. slope of th

44、e indifference curve2. MRS = x2/x1 along an indifference curve. Figure 3.11.3. sign problem natural sign is negative, since indifference curves willgenerally have negative slope4. measures how the consumer is willing to trade off consumption of good 1 for consumption of good 2. Figure 3.12.Chapter 3

45、 95. measures marginal willingness to pay (give up)a) not the same as how much you have to payb) but how much you would be willing to pay10 Chapter HighlightsChapter 4UtilityIn this chapter, the level of abstraction kicks up another notch.s oftenhave trouble with the idea of utility. It is sometimes

46、 hard for trained economiststo sympathize with them sufficiently, since it seems like such an obvious notion to us.Here is a way to approach the subject. Suppose that we return to the idea of the “heavier than” relation discussed in the last chapter. Think of having a big balance scale with two tray

47、s. You can put someone on each side of the balancescale and see whichis heavier, but you dont have any standardizedweights. Nevertheless you have a way to determine whether x is heavier than y.Now suppose that you decide to establish a scale. You get a bunch of stones, check that they are all the sa

48、me weight, and then measure the weight of individuals in stones. It is clear that x is heavier than y if xs weight in stones is heavier than ys weight in stones.Somebody else might use different units of measurementskilograms, pounds, or whatever. It doesnt make any difference in terms of deciding w

49、ho is heavier. At this point it is easy to draw the analogy with utilityjust as pounds give a way to represent the “heavier than” order numerically, utility gives a way to represent the preference order numerically. Just as the units of weight are arbitrary, so are the units of utility.This analogy

50、can also be used to explore the concept of a positive monotonictransformation, a concept thats have great trouble with. Tell them thata monotonic transformation is just like changing units of measurement in the weight example.However, it is also important fors to understand that nonlinearchanges of

51、units are possible. Here is a nice example to illustrate this. Supposethat wood is always sold in piles shaped like cubes. Think of the relation “one pile has more wood than another.” Then you can represent this relation by looking at the measure of the sides of the piles, the surface area of the pi

52、les, or the volume of the piles. That is, x, x2, or x3 gives exactly the same comparisonbetween the piles. Each of these numbers is a different representation of theutility of a cube of wood.Be sure to go over carefully the examples here. The Cobb-Douglas example is an important one, since we use it

53、 so much in the workbook. Emphasize that it is just a nice functional form that gives convenient expressions. Be sure toChapter 4 11elaborate on the idea that xaxb is teral form for Cobb-Douglas preferences,1 2but various monotonic transformations (e.g., the log) can make it look quitedifferent. Its

54、 a good idea to calculate the MRS for a few representations of the Cobb-Douglas utility function in class so that people can see how to do them and, more importantly, that the MRS doesnt change as you change the representation of utility.The example at the end of the chapter, on commuting behavior,

55、is a verynice one. If you present it right, it will convince yours that utility is anoperational concept. Talk about how the same methods can be used in marketing surveys, surveys of college admissions, etc.The exercises in the workbook for this chapter are very important since theydrive home the id

56、eas. A lot of times,s think that they understand somepoint, but they dont, and these exercises will point that out to them. It isa good idea to let thes discover for themselves that a sure-fire way totell whether one utility function represents the same preferences as another is to compute the two m

57、arginal rate of substitution functions. If they dont get this idea on their own, you can pose it as a question and lead them to the answer.UtilityA. Two ways of viewing utility1. old waya) measures how “satisfied” you are1) not operational2) many other problems2. new waya) summarizes preferencesb) a utility function assigns a number to each bundle of goods so that more preferred bundles