Economics 1 - Fall 2003 - Train - Final

Econometrics IChina Center for Economic Research, Peking UniversityMinggao Shen, Fall 2003Office: 621 CCER; Phone: 6275-3109; Email: mshen@.Office Hour: Mondays 11:00-12:00amTA: Fei XU, phoenix-xf@Class Meets: Wednesdays 1:30-4:20 pm; TA Session: TBACourse DescriptionThis is an introductory graduate level course in Econometrics. This course helps students understand and use regression. In addition, the course should give students insight into how to correct some common problems found in estimation. As such, the lectures will tend to emphasize the practical uses of econometric theory, and students will have considerable opportunity to put this to use in computer-based assignments. At the end of the course, it is expected that students will be able to conduct their own empirical investigations, as well as to critically evaluate econometric and other statistical evidence.Required TextbooksEconometric Analysis, by William H. Green (Fifth Edition), FT Prentice Hall, 2003. (WG)Econometric Analysis of Cross Section and Panel Data, by Jeffrey M. Wooldridge, The MIT Press, 2002. (JW1)Recommended TextbookIntroductory Econometrics: A Modern Approach, by Jeffrey M. Wooldridge.South-Western College Publishing, 2000. (JW2)PrerequisitesProbability and Statistics, Calculus, Linear AlgebraHomeworkThere are weekly graded homework assignments. They will involve both theoretical and empirical exercises. Homework assignments are due in a week.Grading PolicyThe course grade will be based on homework assignments and, a midterm exam, and a final exam. Both exams are open book ones. The weights are:Homework 30%Exam 30%Midterm40%ExamFinalCourse Outline1 Econometrics and Data: An Introduction (WG, Ch.1; JW1, Ch. 1)2 The Simple Regression Model (JW2, Ch. 2)3 The Multiple Linear Regression Model (WG, Ch. 2,3)PropertiesSampleSmallHoliday4 Large Sample Theory (WG, Ch. 5)5 Maximum Likelihood Estimation (WG, Ch. 17)6 Data Problems (JM1, Ch. 4,5)MulticollinearityErrorsMeasurementErrorsUnobservable7 Functional Form and Model Selection (WG, Ch. 7,8; JW1, Ch. 6)VariablesOmittedExtraneousVariablesEndogeneityEstimationInstrumentalVariablesMidterm Exam8 The Nonlinear Regression Model (WG, Ch. 9)9/10 Generalized Regression Models (WG, Ch. 10,11,12,19) HeteroskedasticitySerial Correlation11/12 Systems of Regression Equations (WG, Ch. 14,15; JW1, Ch. 7,9) The Seemingly Unrelated Regression ModelThe Simultaneous Equations Model13 The Generalized Method of Moments (WG, Ch. 18)14 The Dynamic Regression Model (WG, Ch. 19)Final Exam。

Economics2010a Fall2003Edward L.Glaeser Lecture22.Choice and Utility Functionsa.Choice in Consumer Demand Theory and Walrasian Demandb.Properties of demand from continuity and properties from WARPc.Representing Preferences with a Utility Functiond.Demand as Derived from Utility Maximizatione.Application:Fertilityx i denotes commodities,continuous numbersx x 1,x 2,....x Lvector of discretecommodities p p 1,p 2,....p L vector of prices w wealth available to be spentThe budget constraint p x i 1Lp i x iwMWG Definition2.D.1The Walrasian Budget SetB p,w x L:p x wis the set of all feasible consumption bundles for the consumer faces market prices p and has wealth w.Note:We will be treating all prices and consumption levels as being weakly positive.Prices are treated as exogenous–as they will be in the production case.While neither consumer nor producer chooses prices(generally)prices are the extra parameter in each side’s problem that ensures that demand and supply are equal.Non-linear prices are certainly possible(example2.D.4).The Walrasian Demand Function is the set C B p,w which is defined for all p,w ,or at least for a full dimensional subsetp,w L 1We generally assume that C B p,w has a single element(for convenience)but it doesn’t need to.We writeC B p,w x p,w x1 p,w ,...x L p,wWe will also generally assume that demand is continuous and differentiable. MWG Definition2.E.1:The Walrasian Demand Function ishomogeneous of degree zero ifx p, w x p,w for any p,w and 0.This property follows from the fact that choice is only a function of the budget set and B p,w x L:p x w is the same set asB p, w x L: p x wThis fairly obvious claim is in many ways the underlying intellectual basis for the economic bias that the price level doesn’t matter.Differentiating x p, w x p,w totally with respect to gives us the following equation:i 1L x k p ,w p i p i x k p ,w ww 0 i 1L x k p ,w p i p i x k x k p ,w w w x k i 1L pi k w k 0This tells you that for any commodity,the sum of own and cross price elasticities equals -1times the income elasticity.MWG Definition2.E.2Walras’Law:The Walrasian Demand correspondence x p,w satisfies Walras’law if for every p 0and w 0,we have p x w for all x x p,w .This just says that the consumer spends all of his wealth.Looking ahead,Walras’law will come about as long as consumers are not “satiated”in at least one of the goods.Walras’Law and differentiability give us two convenient equalities.Differentiating p x w with respect to w yields:i 1Lp i x i p ,w w 1or manipulating this slightly yields:i 1L x i p ,w w w x i p i x i w i 1Lw i i0,where i p i x i w ,the budget share of good i .This means that income elasticities (when weighted by budget shares)sum to one.All goods can’t be luxuries,etc.Sometimes this is known as Engel aggregation (income effects are after all drawn with Engel curves).Differentiating p x w with respect to p k yields:i 1Lp i x i p ,wp k x k 0or multiplying the whole expression by p k w : i 1L x i p ,w p k p k x i p i x i w p k x k w i 1Lp k ii k0,where again i p i x i wThis means that cross price elasticities sum to-1times the budget share of the relevant good.Overall,these elasticities have to sum to a negative number.MWG Definition2.F.1The Walrasian Demand function satisfies the weak axiom of revealed preference if the following property holds for any two price-wealth situations p,w and p ,w : If p x p ,w w and x p ,w x p,wthen p x p,w w .In words–if the goods that are chosen with budget set(a)are affordable at budget set (b),and not the same as the goods that are chosen at budget set(b),then the goods that are chosen at budget set(b) are not affordable at budget set(a).Just like in the last lecture,WARP meansthat if bundle(b)is preferred to bundle(a) in one setting,it will be preferred in all other settings.A property that follows from WARP:price changes that are fully income compensated make consumers weakly better off.Take any p,w and let p p p Compensate the consumer with an income change so that the old bundle is exactly affordable at the new prices,i.e.:w w w x p,w pThe consumer’s new consumption level atp ,w satisfies the WARP condition:p x p,w w ,which then implies thatp x p ,w w,and this holds with strict equality whenx p ,w x p,wGiven that the consumer could have chosen the old bundle,the consumer must have weakly preferred the new bundle.MWG Proposition2.F.1:WARP implies the law of compensated demand.If the Walrasian demand function x p,w satisfies Walras’Law and is homogeneous of degree zero,then x p,w satisfies the weak axiom if and only if the following property holds.For any compensated price change from an initial situation p,w to a new price wealth pair p ,w p ,p x p,x ,then p p x p ,w x p,x 0,and this equality holds strictly whenx p ,w x p,x .We are now interested only in the weakaxiom- law of demand part of the proposition.First,note that if x p ,w x p,w we’re done,so consideronly the case where x p ,w x p,w . In that case,Walras’law gives us:p x p ,w w ,and we havedefined w so that w p x p,w Together,this gives us thatp x p ,w x p,w 0But we also know that as p ,w satisfies theWARP condition:p x p,w w andx p ,w x p,wit follows that p x p ,w w.Using p x p,w w(again by Walras’Law),this gives us that:p x p ,w x p,w 0Subtraction then yields:p p x p ,w x p,w 0 Change in prices times change in quantities is negative.Since p x 0for all compensated price changes,this also holds in the limit for very small price changes and dp dx 0.We can use matrix notation and write:dx D p x p ,w dp D w x p ,w dwwhich just means:dxi 1L x 1 p i dp i x 1 w dw ,.., i 1L x L p i dp i x L w ordx D p x p ,w dp D w x p ,w x p ,w dp ordxD p x p ,w D w x p ,w x p ,wT dpThe D p x p ,w D w x p ,w x p ,wTterm is a matrix where the element in row i ,column j of the matrix isx ip k x i w xkx 1 p 1 x 1 w x 1....x 1 p L x 1w x L.............x L p 1 x L w x 1.... x L p L x Lw xLand thendpD p x p ,w D w x p ,w x p ,wT dp 0The term in brackets is the Slutsky matrix.MWG Proposition2.F.2:If a differentiable Walrasian demand function x p,w satisfies Walras’law, homogeneity of degree zero and WARP, then at any p,w the Slutsky matrix is negative semi-definite,i.e.v Sv 0for any v L.MWG Proposition2.F.3:Suppose that the Walrasian demand function x p,w is differentiably homogeneous of degree zero,and satisfies Walras’Law.Then p S p,w 0 and S p,w p 0for any p,wUtility Functions–Finally getting to the basic tool of99%ofeconomics.Back to preferences.We want fourattributes:(1)completeness and(2)transitivityThese were defined in lecture1and we refer to preferences with these attributes as being rational.Definition3.B.2.:The preference relation on X is monotone if x,y X,and y x impliesy x.It is strongly monotone if y x and y x implies y x.In many cases,we won’t naturally have monotonicity,but then a little redefinition of variables does the trick(turn a bad into a good by multiplying by-1).A slight twist(I mentioned this earlier):Definition3.B.3:The preference relation on Xis locally nonsatiated if for every x,y X,and every0,there exists a ysuch that y x and y x.This means that there exists a y vector that is arbitrarily close to x that is strictly preferred to x.One last property:Definition 3.C.1.:The preference relation on X is continuous if it is preserved under limits.That is,for any sequence of pairs x n ,y n n 1 with x n y n for all n ,x lim n x n and y lim n y n we have x y .The famous counterexample islexicographic preferences,where more of good 2is preferred to less,but unless the bundles have thesame amount good 1,then the bundle with more good 1is always preferred.Consider sequence 1,with no units of good 2and 1/n units of good 1,and sequence 2with no units of good 1,and1 1/n units of good2.For all finite n,sequence1is preferred to sequence1,but in the limit sequence1 yields zero unit of either good and sequence2yields1unit of good2and is therefore preferred.Lexicographic preferences are a famous example,but hardly amainstay of either theory or empirical work.MWG Definition1.B.2:A functionu:X is a utility function representing preference relation if for all x,y X, x y if and only if u x u y Proposition3.C.1:If the rational preference relation on L is continuous, then there is a continuous utility functionu x that represents .The proof in MWG requires monotonicity–a slight variant is toto take a probability measure on L that has positive density everywhere,and then letu x 1 prob y y x .By construction,if x y then u x u y and if u x u y then x y.Now we’ve gotten to a utility function and we know that it is continuous.MWG Definition3.B.4:The preference relation is convex if for every x X the upper contour sety Y:y x is convex,that is if y x and z x then y 1 z x for every 0,1 .MWG Definition3.B.5:The preference relation is strictly convex if for every x X if y x and z x andy z implies that y 1 z x for every 0,1 .Convex preferences imply that u . is quasi-concave,i.e.the sety L:u y u xis concave(equivalentlyu y 1 x Min u x ,u y for any x,y and all 0,1 .Strict convexity implies strictquasi-concavity.The utility maximization problem is to maximize u x subject to theconstraint p x 0.MWG Proposition3.D.1:If p 0and u . is continuous then the utility maximization problem has a solution. The proof relies on the fact that a continuous function always has a maximum on a compact set,so you just need to show that the budget set is closed and bounded,pact.Proposition3.D.2:Suppose that u . is a continuous utility functionrepresenting a locally non-satiated preference relation defined on the consumption set X L.Then the Walrasian demand correspondence has the following properties:(1)x p,w is homogeneous of degree zero in prices and wealth,i.e.x p,w x p, w for every 0(2)Walras’law p x p,w w(3)If is convex so that u . isquasi-concave,then x p,w is a convex set.Moreover if is strictly convex,so that u . is strictly quasi-concave,then x p,w consists of a single element.In practice,we write down a Langrangianmax x, U x1,x2,...x Lwi 1Lp i xiwhich yields us a system of first order conditions:U x1,x2,...x Lx ip iThese are L equations and we have L 1 unknowns,so we need to use the budget set as well to solve the problem.An application:fertility decisions.Many empirical puzzles:(1)Why does fertility drop with income so substantially across countries?(2)Why is fertility below replacement in all of Europe,but not in the U.S.?How would we capture this:Begin with U C,N –utility over consumption and kids.Assume that kids have both a cash cost(k),and a time cost(t)Assume that you have a time budget that can either be used producing kids or making money.Write down the total budget constraintWT Y C k tW NSolving C from the budget set the agent’s maximization problem reduces toU WT Y k tW N,NmaxNWhich in turn produces a F.O.C.k tW U1 WT Y k tW N,NU2 WT Y k tW N,N 0 where U1is the partial w.r.t.the1st argumentof U and similarly for U2.The marginal utility of another kid is weighed off against the marginal cost in terms of time and money.Comparative statics can be derived by (1)Using the implicit function theorem to define N Z ,where Z is a vectorrepresenting all of the parameters in this equation(i.e.,Z t,T,Y,W,k )and(2)Totally differentiating the F.O.C.to findNZ.LetF N,Z k tW U1 WT Y k tW N,NU2 WT Y k tW N,Nso that the F.O.C is F N Z ,Z 0.Differentiation w.r.t parameter Z then gives us:F1 N Z ,Z NZF2 N Z ,Z 0 from whichN Z F2 NZ ,ZF1 N Z ,Z.In this caseF1 N ,Z k tW 2U11 C ,N U22 C ,NU22 C ,N 2 k tW U12 C ,N and C WT Y k tW N .We generally assume that terms likeF1 N Z ,Z are negative(Why?)so thesign of Ndepends entirely on the sign ofZF2 N ,Z F N ,Z.ZIn the case of Z Y for example:Y k tW U1 WT Y k tW N ,N U2 WT Y k tW N ,Nk tW U11 WT Y k tW N ,N U12 WT Y k tW N ,NWhat can we say about this?Does this give us any intuition about anything?In the case of W:W k tW U1 WT Y k tW N ,N U2 WT Y k tW N ,Nk tW T tN U11 WT Y k tW N ,N T tN U12 WT Y k tW N ,NtU1 WT Y k tW N ,NIt’s the same as the unearned incomeeffect expect for the third term.What doesthat third term represent?Now let’s get a little more fancy and assume that parents care about both quantity and quantity,i.e.U C,Q,N .For simplicity assume utility is a separableand quasi-linear in consumption,soU C,Q,N C V Q,Z Q W N,Z N . Assume children cost WtQN.Then the first order conditions are:V Q,Z QWtNQandW N,Z NWtQNIf a parameter increases the marginal return to quality–this will have the following effect2V Q,Z QQ2 QZ Q2V Q,Z QQ Z QWt NZ Qand2W N,Z NN2 NZ QWt QZ Qor QZ Q2V Q,Z QQ Z Q2V Q,ZQQ2Wt 22W N,Z NN2and NZ Q2V Q,Z QQ Z Q2V Q,ZQQ22W N,Z NN2Wt 2How can we sign these two things?Each equation also tells you that the price per child rises as the quality of each child increases,and the price of quality rises as the number of children rises.Through the budget set there is an inherent substitutability between quantity and quality of children.。

2003年全国硕士研究生入学统一考试英语试题Section II Use of EnglishDirections:Read the following text. Choose the best word (s) for each numbered blank and mark [A], [B], [C] or [D] on ANSWER SHEET 1.(10 points)Teachers need to be aware of the emotional, intellectual, and physical changes that young adults experience. And they also need to give serious 21 to how they can best 22 such changes. Growing bodies need movement and 23, but not just in ways that emphasize competition. 24 they areadjusting to their new bodies and a whole host of new inteHectual and emotional challenges,teenagers are especially self-conscious and need the 25 that comes from achieving success andknowing that their accomplishments are 26 by others. However, the typical teenage lifestyle isalready filled with so much competition that it would be 27 to plan activities in which there aremore winners than losers, 28 , publishing newsletters with manystudent-written book reviews, 29 student artwork, and sponsoring book discussion clubs. A variety of small clubs can provide 30 opportunities for leadership, as well as for practice in successful31 dynamics. Making friends is extremely important to teenagers, and many shy students need the32 of some kind of organization with a supportive adult 33 visible in the background.In these activities, it is important to remember that the young teens have 34 attention spans. A variety of activities should be organized 35 participants can remain active as long as they want and then go on to 36 else without feeling guilty and without letting the other participants 37 . This doesnot mean that adults must accept irresponsibility. 38 , they can help students acquire a sense of commitment by 39 for roles that are within their 40 and their attention spans and by having clearly stated rules.21. [A] thought [B] idea [C] opinion [D] advice22. [A] strengthen [B] accommodate [C] stimulate [D] enhance23. [A] care [B] nutrition [C] exercise [D] leisure24. [A] If [B] Although [C] Whereas [D] Because25. [A] assistance [B] guidance [C] confidence [D] tolerance26. [A] claimed [B] admired [C] ignored [D] surpassed27. [A] improper [B] risky [C] fair [D] wise28. [A] in effect [B] as a result [C] for example [D] in a sense29. [A] displaying [B] describing [C] creating [D] exchanging30. [A] durable [B] excessive [C] surplus [D] multiple31. [A] group [B] individual [C] personnel [D] corporation32. [A] consent [B] insurance [C] admission [D] security33. [A] particularly [B] barely [C] definitely [D] rarely34. [A] similar [B] long [C] different [D] short35. [A] if only [B] now that [C] so that [D] even if36. [A] everything [B] anything [C] nothing [D] something37. [A] off [B] down [C] out [D] alone38. [A] On the contrary [B] On the average[C] On the whole [D] On the other hand39. [A] making [B] standing [C] planning [D] taking40.[A] capabilities [B] responsibilities [C] proficiency[D] efficiencySection III Reading ComprehensionPart ADirections:Read the following four texts. Answer the questions below each text by choosing [A], [B], [C] or [D]. Mark your answers on ANSWER SHEET 1 (40 points)Text 1Wild Bill Donovan would have loved the Internet. The American spymaster who built the Office of Strategic Services in the World War II and later laid the roots for the CIA was fascinated with information. Donovan believed in using whatever tools came to hand in the u great game“ of espionage -- spying as a "profession.v These days the Net, which has already re-made such everyday pastimes as buying books and sending mail, is reshaping Donovan's vocation as well.The latest revolution isn't simply a matter of gentlemen reading other gentlemen\ e-mail. That kind of electronic spying has been going on for decades. In the past three or four years, the World Wide Web has given birth to a whole industry of point-and-click spying. The spooks call it “open-source inte lligence,“ and as the Net grows, it is becoming increasingly influential. In 1995 the CIA held a contest to see who could compile the most data about Burundi. The winner, by a large margin, was a tiny Virginia company called Open Source Solutions, whose clear advantage was its mastery of the electronic world.Among the firms making the biggest splash in this new world is Straitford. Inc., a private intelligence-analysis firm based in Austin, Texas. Straitford makes money by selling the results of spying (covering nations from Chile to Russia) to corporations like energy-services firm McDermott International. Many of its predictions are available online at .Straitford president George Friedman says he sees the online world as a kind of mutually reinforcing tool for both information collection and distribution, a spymaster's dream. Last week his firm was busy vacuuming up data bits from the far corners of the world and predicting a crisis in Ukraine. "As soon as that report runs, we'll suddenly get 500 new Internet sign-ups from Ukraine；' says Friedman, a fbnner political science professor. "And we41 hear back from some of them.” Open-source spying does have its risks, of course, since it can be difficult to tell good iiifbniiation from bad. That's where Straitford earns its keep.Friedman relies on a lean staff of 20 in Austin. Several of his staff members have military-intelligence backgrounds. He sees the firm's outsider status as the key to its success. Straitfordbriefs don't sound like the usual Washington back-and-forthing, whereby agencies avoid dramatic declarations on the chance they might be wrong. Straitford, says Friedman, takes pride in its independent voice.41.The emergence of the Net has.|A] received support from fans like Donovan|B] remolded the intelligence services[C] restored many common pastimes|D] revived spying as a profession42.Donovan's story is mentioned in the text to.|A] introduce the topic of online spying[B]show how he fought for the U.S.[C]give an episode of the information war|D] honor his unique services to the CIA43.The phrase “making the biggest splash” (Line 1, Paragraph 3) most probably means.|A] causing the biggest trouble|B] exerting the greatest effort[C] achieving the greatest success|D] enjoying the widest popularity44.It can be learned from Paragraph 4 that.[A]Straitford's prediction about Ukraine has proved true[B]Straitford guarantees the tnithfulness of its information[C]Straitford\ business is characterized by unpredictability[D]Straitford is able to provide fairly reliable information45.Straitford is most proud of its.|A] official status[B]nonconformist image[C]efficient staff|D] military backgroundText 2To paraphrase 18th-century statesman Edmund Burke, “all that is needed for the triumph of a misguided cause is that good people do nothing." One such cause now seeks to end biomedical research because of the theory that animals have rights ruling out their use in research. Scientists need to respond forcefully to animal rights advocates, whose arguments are confusing the public and thereby threatening advances in health knowledge and care. Leaders of the animal rights movement target biomedical research because it depends on public funding, and few people understand the process of health care research. Hearing allegations of cruelty to animals in research settings, many are perplexed that anyone would deliberately harm an animal.For example, a grandmotherly woman staffing an animal rights booth at a recent street fair was distributing a brochure that encouraged readers not to use anything that comes from or is tested in animals—no meat, no fur, no medicines. Asked if she opposed immunizations, she wanted to know if vaccines come from animal research. When assured that they do, she replied, u Theii I would have to say yes." Asked what will happen when epidemics return, she said, "Don't worry, scientists will find some way of using computers." Such well-meaning people just don't understand.Scientists must communicate their message to the public in a compassionate, understandable way -- in human terms, not in the language of molecular biology. We need to make clear the connection between animal research and a grandmother^ hip replacement, a father's bypass operation, a baby's vaccinations, and even a pet's shots. To those who are unaware that animal research was needed to produce these treatments, as well as new treatments and vaccines, animal research seemswasteful at best and cruel at worst.Much can be done. Scientists could “adopt“ middle school classes and present their own research. They should be quick to respond to letters to the editor, lest animal rights misinformation go unchallenged and acquire a deceptive appearance of tiuth. Research institutions could be opened to tours, to show that laboratory animals receive humane care. Finally, because the ultimate stakeholders are patients, the health research community should actively reciuit to its cause not only well-known personalities such as Stephen Cooper, who has made courageous statements about the value of animal research, but all who receive medical treatment. If good people do nothing, there is a real possibility that an uninformed citizeniy will extinguish the precious embers of medical progress.46.The author begins his article with Edmund Burke's words to.[A]call on scientists to take some actions|B] criticize the misguided cause of animal rights[C]warn of the doom of biomedical research[D]show the triumph of the animal rights movement47.Misled people tend to think that using an animal in research is.|A] cruel but natural[B]inhuman and unacceptable[C]inevitable but vicious|D] pointless and wasteful48.The example of the grandmotherly woman is used to show the public's[A]discontent with animal research|B] ignorance about medical science[C]indifference to epidemics[D]anxiety about animal rights49.The author believes that, in face of the challenge from animal rights advocates, scientistsshould.[A]communicate more with the public|B] employ hi-tech means in research[C]feel no shame for their cause[D]strive to develop new cures50.From the text we learn that Stephen Cooper is.|A] a well-known humanist|B] a medical practitioner[C] an enthusiast in animal rights|D] a supporter of animal researchText 3In recent years, railroads have been combining with each other, merging into supersystems, causing heightened concerns about monopoly. As recently as 1995, the top four railroads accounted for under 70 percent of the total ton-miles moved by rails. Next year, after a series of mergers is completed, just four railroads will control well over 90 percent of all the freight moved by major rail carriers.Supporters of the new supersystems argue that these mergers will allow for substantial cost reductions and better coordinated service. Any threat of monopoly, they argue, is removed by fierce competition from trucks. But many shippers complain that for heavy bulk commodities traveling long distances, such as coat chemicals, and grain, trucking is too costly and the railroads therefore have them by the throat.The vast consolidation within the rail industry means that most shippers are served by only one rail company. Railroads typically charge such “captive“ shippers 20 to 30 percent more th an they do when another railroad is competing for the business. Shippers who feel they are being overcharged have the right to appeal to the federal government's Surface Transportation Board for rate relief, but the process is expensive, time-consuming, and will work only in truly extreme cases.Railroads justify rate discrimination against captive shippers on the grounds that in the long run it reduces everyone's cost. If railroads charged all customers the same average rate, they argue, shippers who have the option of switching to trucks or other forms of transportation would do so, leaving remaining customers to shoulder the cost of keeping up the line. It's a theory to which many economists subscribe, but in practice it often leaves railroads in the position of determining which companies will flourish and which will fail. u Do we really want raikoads to be the arbiters of who wins and who loses in the marketplace?^ asks Martin Bercovici, a Washington lawyer who frequently represents shippers.Many captive shippers also worry they will soon be hit with a round of huge rate increases. The railroad industry as a whole, despite its brightening fortunes, still does not earn enough to cover the cost of the capital it must invest to keep up with its surging traffic. Yet railroads continue to borrow billions to acquire one another, with Wall Street cheering them on. Consider the $10.2 billion bid by Norfolk Southern and CSX to acquii'e Conrail this year. Conrail's net railway operating income in 1996 was just $427 million, less than half of the canyiiig costs of the transaction. Who's going to pay for the rest of the bill? Many captive shippers fear that they will, as Norfolk Southern and CSX increase their grip on the market.51.According to those who support mergers, railway monopoly is unlikely because *|A] cost reduction is based on competition[B]services call for cross-trade coordination[C]outside competitors will continue to exist[D]shippers will have the railway by the throat52.What is many captive shippers5 attitude towards the consolidation in the rail industry?[A] Indifferent.|B] Supportive.[C] Indignant.|D] Apprehensive.53.It can be inferred from Paragraph 3 that.[A]shippers will be charged less without a rival railroad|B] there will soon be only one railroad company nationwide[C]overcharged shippers are unlikely to appeal for rate relief[D] a government board ensures fair play in railway business54.The word “arbiters” (Line 7, Paragraph 4) most probably refers to those[A]who work as coordinators[B]who function as judges[C]who supervise transactions[D]who determine the price55.According to the text, the cost increase in the rail industry is mainly caused by *[A]the continuing acquisition[B]the growing traffic[C]the cheering Wall Street[D]the shrinking marketText 4It is said that in England death is pressing, in Canada inevitable and in California optional. Small wonder. Americans5 life expectancy has nearly doubled over the past century. Failing hips can be replaced, clinical depression controlled, cataracts removed in a 30-minute surgical procedure. Such advances offer the aging population a quality of life that was unimaginable when I entered medicine 50 years ago. But not even a great health-care system can cure death -- and our failure to confront that reality now threatens this greatness of ours.Death is normal; we are genetically programmed to disintegrate and perish, even under ideal conditions. We all understand that at some level, yet as medical consumers we treat death as a problem to be solved. Shielded by third-party payers from the cost of our care, we demand everything that can possibly be done for us, even if it's useless. Tlie most obvious example is late-stage cancer care. Physicians -- fiustrated by their inability to cure the disease and fearing loss of hope in the patient --too often offer aggressive treatment far beyond what is scientifically justified.In 1950, the U.S. spent $12.7 billion on health care. In 2002. the cost will be $1,540 billion. Anyone can see this trend is unsustainable. Yet few seem willing to try to reverse it. Some scholars conclude that a government with finite resources should simply stop paying for medical care that sustains life beyond a certain age -- say 83 or so. Former Colorado governor Richard Lamm has been quoted as saying tha t the old and infirm “have a duty to die and get out of the way,“ so that younger, healthier people can realize their potential.I would not go that far. Energetic people now routinely work through their 60s and beyond, and remain dazzlingly productive. At 78, Viacom chairman Sumner Redstone jokingly claims to be 53. Supreme Court Justice Sandra Day O'Connor is in her 70s, and former surgeon general C. Everett Koop chairs an Internet start-up in his 80s. These leaders are living proof that prevention works and that we can manage the health problems that come naturally with age. As a mere 68-year-old.I wish to age as productively as they have.Yet there are limits to what a society can spend in this pursuit. As a physician, I know the most costly and dramatic measures may be ineffective and painful. I also know that people in Japan and Sweden, countries that spend far less on medical care, have achieved longer, healthier lives than we have. As a nation, we may be overfunding the quest for unlikely cures while underfunding research on humbler therapies that could iinpiove people's lives.56.What is implied in the first sentence?[A]Americans are better prepared for death than other people.[B]Americans enjoy a higher life quality than ever before.[C]Americans are over-confident of their medical technology.[D]Americans take a vain pride in their long life expectancy.57.The author uses the example of cancer patients to show that.[A]medical resources are often wasted[B]doctors are helpless against fatal diseases[C]some treatments are too aggressive[D]medical costs are becoming unaffordable58.The author's attitude toward Richard Lamm's remark is one of.[A]strong disapproval[B]reserved consent[C]slight contempt|D] enthusiastic support59.In contrast to the U.S., Japan and Sweden are funding their medical care[A]more flexibly[B]more extravagantly[C]more cautiously[D]more reasonably60.The text intends to express the idea that.[A]medicine will further prolong people's lives[B]life beyond a certain limit is not worth living[C]death should be accepted as a fact of life|D] excessive demands increase the cost of health carePartBDirections:Read the following text carefully and then translate the underlined segments into Chinese. Your translation should be written clearly on ANSWER SHEET 2. (10 points)Human beings in all times and places think about their world and wonder at their place in it. Humans are thoughtful and creative, possessed of insatiable curiosity. 61) Furtheimorg humans have the ability to modify the environment in which [hey live, thus subjecting all other life foirns to their own peculiar ideas and fancies. Therefore, it is important to study humans in all their richness and diversity in a calm and systematic manner, with the hope that the knowledge resulting from such studies can lead humans to a more harmonious way of living with themselves and with all other life forms on this planet Earth.“Anthropology“ derives from the Greek words anthropos: "human^ and logos “the study of." By its very name, anthropology encompasses the study of all humankind.Anthropology is one of the social sciences. 62) Social science is that branch of intellectual enquiry which seeks to study humans and their endeavors in the same reasoned、orderly, systematic, and dispassioned manner that Mural scientists use for the study of natural phenomena.Social science disciplines include geography, economics, political science, psychology, and sociology. Each of these social sciences has a subfield or specialization which lies particularly close to anthropology.All the social sciences focus upon the study of humanity. Anthropology is a field-study oriented discipline which makes extensive use of the comparative method in analysis. 63) The emphasis on data gathered first-hand, combined with a cross-cultural perspective brought [o the analysis of cultures past and present, makes this study a unique and distinctly important social science.Anthropological analyses rest heavily upon the concept of culture. Sir Edward Tylor's formulation of the concept of culture was one of the great intellectual achievements of 19th century science. 64) Tylor defined culture as ”・・・ that complex whole which includes belief, art, morals, law、custom. and any other capabilities and habits acquired by man as a member of society." This insight, so profound in its simplicity, opened up an entirely new way of perceiving and understanding human life. Implicit within Tylor,s definition is the concept that culture is learned, shared, and patterned behavior.65) Thus, the anlhropological coocept of “culture." like the concept of “set" in mathematics, is an abstract concept which makes possible immense amounts of conciete research and understanding.Section IV Writing66. Directions:Study the following set of drawings carefully and write an essay in which you should1)describe the set of drawings, interpret its meaning, and2)point out its implications in our life.You should write about 200 words neatly on ANSWER SHEET 2. (20 points)温室国医不起血雨。

武汉大学2003攻读硕士学位研究生入学考试试题考试科目:现代经济理论(含宏、微观经济学) 科目代码：４６１1. (25’) Consider an economic model in which the production function can be written as 10 1≤+=−ββa g L K Y a a p , here g is the government spending per capita, K, L, Y are aggregate capital, population and output respectively. The government spending is financed by an income tax, i.e., Y Lg G τ==. Capital accumulation equation is K sY K δ−=. Suppose the saving rate s ,income tax rate τ,depreciation rate δand population growth rate n are given exogenously, S+τ＜1.(1)Show that if 1p βα+, then the capital stock per capita will convergesto a steady-state value k * which is positively correlated with income tax rate τ.(2)Show that if 1=+βα, then the capital stock per capital will increase with a constant growth rate if δτ+n s f .2. (25’) Consider an economy with identical long-lived individuals whose utility functions can be written as 10 0, ,]lnk lnc [t t 0p p f βγγβdt e t +∫−∞, her c t ,k t are consumption and capital stock per capita in time t. Suppose the population growth rate is zero. The capital accumulation equation is 1a 0 ,p p k c Ak k a δ−−=.Solve the steady state values of consumption, capital stock and output per capita.3. (25’) Consider an OLG model in which each individual can live two period. Individuals’ utility function can be written as 12t 1t lnc lnc ++=βt U , here c 1t and c 2t+1 are the consumptions in period t of young and old individuals respectively. Individual’s wealth constraints are,1t t t w s c =+ )1(112+++=t t t r s cHere w t , s t and r t+1 are wage, saving and interest rate respectively. Production function can be written as at t Ak y =. Suppose that the depreciation rate δ＝1 and population growth rate are zero. Assumption the government levies an output tax with a constant tax rate τ.(1) Solve the steady state values of capital stock and output per capita.(2) Show that the relationship between the tax income of the government and tax rate can be described as a Laffer Curve, i.e., as the tax rate increase, the tax income increases when the tax rate is small and decreases when it is large enough. Solve the tax rate with the maximum tax income.4. (25’) If preferences are locally nonsatiated, and if (x *,y *,p )is anequilibrium with transfers, then the allocation(x *,y *)is Pareto optimal.5. (25’) If preference i ≥ is homothetic, assume that x i (p,w i ) is differentiable, then x i (p,w i ) satisfies the uncompensated law of demand property.6. (25’) Suppose that production set Y is convex. Then every efficient production Y y ∈is a profit-maximizing production for some nonzero price vector 0≥p .答案部分武汉大学2003攻读硕士学位研究生入学考试试题考试科目:现代经济理论(含宏、微观经济学) 科目代码：４６１1. Consider an economic model in which the production function can be written as 10 1≤+=−ββa g L K Y a a p , here g is the government spending per capita, K, L, Y are aggregate capital, population and output respectively. The government spending is financed by an income tax, i.e., Y Lg G τ==. Capital accumulation equation is K sY K δ−=. Suppose the saving rate s ,income tax rate τ,depreciation rate δand population growth rate n are given exogenously, S+τ＜1.(1) Show that if 1p βα+, then the capital stock per capita will convergesto a steady-state value k * which is positively correlated with income tax rate τ.(2)Show that if 1=+βα,then the capital stock per capital will increase with a constant growth rate if δτ+n s f .2. Consider an economy with identical long-lived individuals whose utility functions can be written as 10 0, ,]lnk lnc [t t 0p p f βγγβdt e t +∫−∞, her c t , k t areconsumption and capital stock per capita in time t. Suppose the population growth rate is zero. The capital accumulation equation is 1a 0 ,p p k c Ak k a δ−−=.Solve the steady state values of consumption, capital stock and output per capita.3. Consider an OLG model in which each individual can live two period. Individuals’ utility function can be written as 12t 1t lnc lnc ++=βt U , here c 1t and c 2t+1 are the consumptions in period t of young and old individuals respectively. Individual’s wealth constraints are,1t t t w s c =+ )1(112+++=t t t r s cHere w t , s t and r t+1 are wage, saving and interest rate respectively. Production function can be written as a t t Ak y =. Suppose that the depreciation rate δ＝1 and population growth rate are zero. Assumption the government levies an output tax with a constant tax rate τ.(1) Solve the steady state values of capital stock and output per capita.(2) Show that the relationship between the tax income of the government and tax rate can be described as a Laffer Curve, i.e., as the tax rate increase, the tax income increases when the tax rate is small and decreases when it is large enough. Solve the tax rate with the maximum tax income.4. If preferences are locally nonsatiated, and if (x *,y *,p )isan equilibrium with transfers, then the allocation(x *,y *)is Pareto optimal.5. If preference i ≥ is homothetic, assume that x i (p,w i ) is differentiable, then x i (p,w i ) satisfies the uncompensated law of demand property.6. Suppose that production set Y is convex. Then every efficient production Y y ∈is a profit-maximizing production for some nonzero price vector 0≥p .。

Economics2010aFall2003 Edward L.Glaeser Lecture99.The Producer’s Problema.Firms and Maximizationb.Production Functionsc.Supply and Profit Functionsd.Cost Functionse.Duality and Producersf.Application:Urban Systems1.TechnologyThe more tradition approach is to assume: (1)A production correspondence,e.g.f(K,L)or more generally f Z ,that maps the vector of inputs Z which cost W into a vector of outputs,which are then sold at prices P for total revenues Pf Z .In many cases,we think of f Z as a function–i.e.only one output–but is doesn’t need to be.We assume first that firms treat prices as given–i.e.they are price takers–i.e.they don’t have market power.(2)We assume that firms maximize profits, and that they have the option(at least in the long run)to exit,i.e.earn zero profits.This is of course a deeply controversial claim.(3)We make some assumption about the number of firms–perhaps free entry of identical firms,perhaps something else. This last assumption gives us a great deal of power–this is the equilibrium assumption in action.Together,profit maximization and free entry of identical firms gives us the following two sets of conditions(assuming that the production function is continuously differentiable and concave).W iP f ZZ ifor each input marginal revenue equals price.And given these first order conditions:Pf Z W Z 0These two,especially,when combined with demand give you implications about prices.Now back to the MWG set theoretic approach.A production plan is a vector y L.This includes both inputs and outputs,and an input is a negative element in this vector.An output is a positive element in this vector.Total profits are p yThe set of all production plans is Y,which is analogous to X,in the consumer chapters.We generally assume that0 Y,so that firms can shut down.Generally,we assume that Y is(1)nonempty(even beyond including0)(2)closed,i.e.includes its limit points.(3)no free lunch–there is no vector y Y where y l 0,for all l and y k 0for at least one factor l k.(4)free disposal–if a vectory1,..y k,..y L Y where y k 0,for then all other vectors y1,..x k,..y L Y wherex k y k(you can always get rid of something).(5)irreversibility:if y Y then y YThese properties are more particular: (6)Nonincreasing returns to scale.Ify Y,then y Y for all 0,1 –you can always scale down.(7)Nondecreasing returns to scale.Ify Y,then y Y for all 1–you can always scale up.(8)Constant returns to scale If y Y,then y Y for all 0–you can always scale up or down.(9)Additivity(also free entry)if y Y and y Y then y y Y(10)Convexity if y Y and y Y theny 1 y Y for all 0,1(11)Y is a convex conde.If for anyy,y Y and 0, 0, y y YMWG Proposition5.B.1:The production set Y is additive and satisfies the nonincreasing returns condition if and only if it is a convex cone.If it is a convex cone–then the nonincreasing returns condition and additivity immediately follow.Let k Max , where k is an integer, then ky,ky Y by additivity.Also using nonincreasing returns to scalek ky Y andkky Y and we’re done.The profit maximization problem is to maximize p y subject to y YThis yields a supply correspondence y p And a profit function p p y pProperties of the profit function MWG Proposition5.C.1:Suppose that . is the profit function of the production set Y,and that y . is the associated supply correspondence. Assume also that Y is closed and satisfies the free disposal property.Then:(1) . is homogeneous of degree one.(2) . is convex(3)y(.)is homogeneous of deree zero(4)If Y is strictly convex,then y(.)is single valued.(5)If y(.)is single valued then . is differentiable and p y p(6)If y(.)is differentiable thenDy p D2 p is a symmetric and positive semidefinite matrix with Dy p p 0Homogeneity of degree one in prices occurs because the vector y that maximizes py subject to any constraint is the same vector that maximizes py subject to the same constraint for any positive .This also gives us homogeneity of degree zero for the supply correspondence.Convexity–p 1 p p 1 p for 0,1 .Let p p 1 p and have y,y and y denote the optimal production vectors at the three price levels.Then we know thatp 1 p py 1 p yBut py py and p y p y and we’re done.Cost minimization–now assume a fixed vector of outputs and a production function f(Z).The cost minimization problem is to minimize W Z subject to f Z Q for some fixed level Q.In principle,this quantity constraint could handle a lot of different outputs,but we will certainly focus on the idea of a single output.The correspondence Z W,Q is the input demand that satisfies cost minimization. The cost function C W,Q W Z W,QProperties of the Cost Function MWG Proposition5.C.2:Suppose that C(W,Q)is the cost function of a single output technology Y,with production function F(.)and that Z(W,Q)is the associated conditional factor demand correspondence.Assume also that Y is closed and satisfies the free disposal property.Then:(1)C(.)is homogeneous of degree one in W(2)C(.)is nondecreasing in Q(3)C(.)is a concave function of W(4)C(.)is homogeneous of degree zero in W.(5)If Z W Q consists of a single point at W then C W Q is differentiable at W and W C W,Q Z W Q (shephard’s lemma)(6)If Z W Q is differentiable at W thenD W Z W,Q D W2C W Q is a symmetric and negative semidefinite matrix withD W Z W,Q W 0(7)If F(.)is homogeneous of degree one then Z(.)and C(.)are also homogeneous of degree one.(8)If F(.)is concave,then C(.)is a convex function of Q.The fact that costs satisfty homogeneity of degree one in input prices follows from the fact that if we scale all prices up by the same constant,the solution to the minimization problem is unchanged.This also gives us that input demand is homogeneous of degree zero.Convexity in costs is directly parallel to concavity of the profit function.C W 1 W ,QC W,Q 1 C W ,Q ,for 0,1 . Let W W 1 W and have Z,Z and Z denote the input vectors at the three price levels.Then we know thatC W 1 W ,Q WZ 1 W Z But WZ WZ and W Z W Z and we’re done.The nondecreasing property follows from free disposal.Lastly Shephard’s lemma follows from the fact that:C W,Q WZ Q F Zwhich has first order conditions:W j F ZZ iDifferentiate this with respect to any W i and we getC W i Z i W j Z j WiF Z ZiZ jW iBut all the terms beyond Z i just drop out (this is the envelope theorem in action).A few production functions to know:Leontief:Y Min 1Z1,... L Z LLinear Y i Z iCobb-Douglas Y Z i iThis is increasing returns if i 1, decreasing returns if i 1and constant returns if i 1Remember you can’t just take logs in this case,but you do know that: i Y W i Z i for all i.This gives you the fact that constant returns technologies are the only ones that yield zero profits.Constant elasticity of substitution: i Z i 1/This yields factor demand ofYW ii11 Z i,for all i.Systems of cities–supply and demand together:Back to compensating differentials.Define consumer utility over non-housing consumption,housing prices and amenities and assume that homes are homogeneous.This means that utility is U W C,A , where C is housing prices.Then indifference across space gives us thatU W C,A UOr if we assume that that communities fall along a continuum:dW dC U1dAU2The increase in wages minus prices must exactly offset the increase in amenities.This is a very famous condition that has been the basis for most of urban economics.But this is only part of the story–there also must be a equilibrium in the product market.Let’s assume that profits equal Pf(L,Z)-WL And assume that free entry pins these down to zero.Then we need to have across space:dZ dW L 0dPf(L,Z) P fZChange in prices times quantity plus price times change in productivity minus change in wage must equal zero.If prices are constant across space(the traded goods assumption–if not they would have to show up in the consumers side as well–you can do this)–we might as well assume P 1and then we havedW 1L f ZThus changes in prices over space must reflect both sides of the market–changes in productivity and changes in either amenities or housing costs.Now we have1L fZU1U2dA dCChanges in housing costs across space add together change in consumer amenities and producer amenities.Now to close the model,we need to think about equilibrium in the housing supply sector.Perhaps homebuilders face a technology G(Q,D)which is their costs per unit built as a function of local characteristics including density,and let g(Q,D)refer to the derivative of this with respect to quantity. Then we have C g(Q,D)anddC gQ dQ gQdDOr1 L fZU1U2dA gQdD gQdQChanges in population across space addtogether these three different forms of local amenities.If for example,D didn’t change over space, then this tells you that the population response to production amenities depends completely on the supply elasticity of housing.。

2003年首都经济贸易大学经济学考研真题及详解一、名词解释1．边际产品价值（VMP）答：边际产品价值（VMP）指在完全竞争条件下，厂商在生产中增加某种生产要素一个单位的投入所增加的产品的价值，等于边际物质产品（MP）与价格（P）的乘积，即：VMP＝MP·P。

因为存在边际收益递减规律，随着这种可变要素投入量的增多，其边际产品递减，从而边际产品价值也逐渐下降，所以边际产品价值曲线为一条自左上方向右下方倾斜的曲线。

在完全竞争条件下，边际产品价值曲线（VMP）与边际收益产品曲线（MRP）互相重合，该生产要素的边际收益产品曲线，同时就是其边际产品价值曲线，从而也就是完全竞争条件下厂商对该生产要素的需求曲线。

在不完全竞争市场上，MR、AR、P 三者不全相等，厂商必须降低商品价格才能出售更多的产品，因此边际收益产品必然小于边际产品价值。

VMP、MRP 两条曲线不再重合，此时仅有厂商的边际收益产品曲线代表了对该种生产要素的需求曲线。

2．帕累托标准答：帕累托标准也称为帕累托最优状态，是指在一个经济体中，资源的任何一种重新配置，已经不可能在其他人的效用水平不下降或福利不减少的情况下使任何一个人的效用水平或福利水平提高的状态。

换言之，社会已达到这样一种情况，即任何变革都不可能使任何人的福利有所增加，而不使其他人的福利减少。

3．投资乘数答：投资乘数指收入的变化与带来这种变化的投资变化量的比率。

投资乘数的大小与居民边际消费倾向有关：居民边际消费倾向越高，投资乘数则越大；居民边际储蓄倾向越高，投资乘数则越小。

即k i＝ΔY/ΔI＝1/（1－b）或k i＝1/（1－MPC）＝1/MPS。

式中，ΔY 是增加的收入，ΔI 是增加的投资，MPC 或b 是边际消费倾向，MPS 是边际储蓄倾向。

投资增加会引起收入多倍增加，投资减少会引起收入成比例减少。

由于这是凯恩斯最早提出来的，所以又称之为“凯恩斯乘数”。

投资乘数发挥作用的前提假设是：①社会中存在闲置资源；②投资和储蓄的决定相互独立；③货币供应量的增加适应支出增加的需要。

对外经济贸易大学2003年攻读硕士学位研究生入学考试（金融学院）金融学：专业基础课（试题代码：471）所有答题（包括英语的判断题和选择题）均做在答卷纸上，并在每题答案前标明各级题号。

答在本试题卷上无效。

本试卷共4页。

一、True-False Questions (1×15=15 points. Please write “T” for true statements or “F” forfales statements following every question number on your answer sheet)1.International investment position is a concept of stocks.n currency market does not belong to European currency market.3.Tariff is of expenditure shifting policies, but monetary policy is just one of expenditure switching policies.4.Yankee bond is a kind of Eurobonds.5.Foreign exchange control is mainly aimed at residents.6.The theoretical foundation of commodity arbitrage is the Law of One Price, so is that of interest arbitrage.7.The meaning of foreign exchange at premium or discount in direct quotation system is just the opposite of that in indirect quotation system.8.Monetary Approach to exchange rate determination is actually another version of Purchasing Power Parity Theory.9.Interest Parity Theory is about determination of short-run exchange rate.10.Buying in the international gold market will increase international reserves.11.Free floating of exchange rate leads to a huge drain on foreign exchange reserves.12.Devaluating native currency may improve on trade account balance.13.In buyer’s credit, payment at sight is required.14.Bretton Woods System can be regarded as an exchange rate system of gold exchange standard.15.Reverse position in IMF is included in general drawing rights.答案：1T 2F 3F 4F 5F 6t 7F 8F 9 T 10F 11F 12F 13F 14F 15F二、Single or Multiple-Choice Questions(2×10=20 points. In each question, at least oneanswer in true. If your choices are right but fewer than the standard, you will still get fewer points. Please write the letters of your choice following every question number on your answer sheet)1.Meade’s conflict will take place in conditions ofa. unemployment and deficit in the balance of paymentsb. unemployment and surplus in the balance of paymentsc. inflation and deficit in the balance of paymentsd. inflation and surplus in the balance of payments2.Which of the following organizations are included in the world bank group?a. International Bank for Reconstruction and Developmentb. International Development Associationc. International Finance Companyd. Bank for International settlements3.Assume that annual interest rate of Great British pound is 21% and that of US dollar is 9%, then according to Interest Parity Theory Great British pound relative to US dollar in 3 monthsforward exchange market will be devaluated bya. 30%b. 12%c. 10%d. 7.5%e. 4%f. 3%4.Bretton Woods System is the result ofa. White Planb. Keynes Planc. Brady Pland. Marshall Plan5.Currencies determining value of SDRs after 1999 includea. Swiss Francb.United State Dollarc. French Francd. Deutsche Marke. Italian Liraf. Great British Poundg. Japanese Yenh. Euro6.According to Balance of Payment Theory of Exchange Rate , which of the following factors will lead to devaluation of native of native currency?a. domestic interest rate level upb. foreign GNP increasedc. native GNP increasedd. domestic price level up7.Eurodollat meansa. US dollar in Europeb. US dollar outside USAc. a general term of US dollars in the whole worldd. US dollar reserve8.In general, a letter of credit isa. irrevocableb. confirmedc. unconfirmedd. transferablee. nontransferable9.In Absorption Approach to the balance of payments , the direct influence of devaluation on absorption includesa. cash balances effectb. terms-of-trade effectc. income redistribution effectd. monetary illusion effecte. idle resources effect10. When economy is in conditions of inflation and deficit in the balance of payments, which of policy mixes should be practiced by Mundell Assignment Rule?a. decreasing fiscal expenditure and raising interest rateb. increasing fiscal expenditure and reducing interest ratec. increasing fiscal expenditure and raising interest rated. decreasing fiscal expenditure and reducing interest rate答案：1ad 2abc 3f 4ab 5cde 6cd 7b 8 9acd 10ac三、简答题（每小题4分，共36分）1.什么是边际效用递减规律？答：（1）基数效用论者的两个基本概念就是总效用和边际效用。

贸易对产业内重新配置和产业总生产率的影响（The Impact of Trade On Intra-industry Reallocations and Aggregate Industry Productivity）Melitz, Marc(2003)，Econometrica; Nov 2003; 71, 6浙江财经大学经济与国际贸易学院茹玉骢翻译\推导并注释摘要：本文发展了一个异质性产业动态模型，分析国际贸易的产业内作用。

模型显示如何开展贸易，会导致更有生产率的企业进入出口市场（同时，一些生产率比较低的企业只在国内市场进行生产），并同时迫使最没有生产率的企业退出市场。

它还表明产业的贸易开放会导致向更有生产率企业的公司之间额外的重新配置。

文章也表明，通过重新配置所导致的产业总生产率的提高带来了福利的改进，从而揭示了以前从未探讨的贸易益处。

本文把Hopenhayn（1992）的动态产业模型结合垄断竞争，在一般均衡中加以讨论。

因此，文章结合生产率的差异，拓展了Krugman1980的贸易模型。

不同生产率的企业共存于一个产业是因为，每个企业在做不可逆转投资进入该产业之前，面临不确的初始生产率。

进入出口市场也是颇费成本，但企业仅在获得其生产率知识后做出出口决定。

1、引言最近的经验研究表明企业之间的生产率存在持续性的差异，另外一些研究也表明生产率高的企业通常会倾向于出口。

文章发展了一个异质性动态产业模型，用来分析国际贸易所祈祷了产业内企业之间配置催化剂作用。

模型重复了许多与贸易相关的微观研究，它显示贸易如何导致那些生产率更高的企业出口，而同时迫使生产率最低的企业退出。

效率最低企业的退出和更有效率企业获得额外出口销售，使得市场份额更趋向于生产率更高的企业，并导致总生产率的提高。

利润也分配给更有生产率的企业。

模型和许多经验研究相吻合，如Bernard and Jensen(1999a)(对美国), Aw, Chung and Roberts(2000)(对台湾),Clerides, Lack and Tybout(1998)（对哥伦比亚、墨西哥和摩洛哥）都, 发现了更有效率企业选择出口市场的证据。