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JudgeÕsCommentary323JudgeÕsCommentary:TheOutstandingGradeInßationPapers

DanielZwillingerWaltham,MA02453zwillinger@alum.mit.edu

Gradepointaverage(GPA)isthemostwidelyusedsummaryofunder-graduatestudentperformance.Unfortunately,combiningstudentgradesus-ingsimpleaveragingtoobtainaGPAscoreresultsinsystematicbiasesagainststudentsenrolledinmorerigorouscurriculaand/ortakingmorecourses.Hereisanexample[LarkeyandCaulkins1992]offourstudents(callthemIÐIV)inwhichStudentIalwaysobtainsthebestgradeineverycoursethatshetakesandStudentIValwaysobtainstheworsegradeineverycoursethathetakes,yetStudentIhasalowerGPAthanStudentIVdoes:

StudentIStudentIIStudentIIIStudentIVCourseGPACourse1B+B−3.00Course2C+C2.15

Course3AB+3.65

Course4C−D1.35

Course5AA−3.85Course6B+B3.15

Course7B+B3.15

Course8B+BB−C+2.83Course9BB−2.85

StudentGPA2.782.862.883.0

TheMCMproblemwastodetermineaÒbetterÓrankingthanoneusingpureGPAs;thisproblemhasnosimpleÒsolution.ÓJohnson[1997]referstomanystudiesofthistopicandsuggestsatechniquethatwasconsideredÑbutnotacceptedÑbythefacultyatDukeUniversity.Eachparticipatingteamistobecommendedforitseffortsintacklingthisproblem.Asinanyopen-endedmathematicalmodelingproblem,thereisnotonlygreatlatitudeforinnovativesolutiontechniquesbutalsotheriskofÞnding

TheUMAPJournal19(3)(1998)323Ð327.c󰀂Copyright1998byCOMAP,Inc.Allrightsreserved.PermissiontomakedigitalorhardcopiesofpartorallofthisworkforpersonalorclassroomuseisgrantedwithoutfeeprovidedthatcopiesarenotmadeordistributedforproÞtorcommercialadvantageandthatcopiesbearthisnotice.Abstractingwithcreditispermitted,butcopyrightsforcomponentsofthisworkownedbyothersthanCOMAPmustbehonored.Tocopyotherwise,torepublish,topostonservers,ortoredistributetolistsrequirespriorpermissionfromCOMAP.324TheUMAPJournal19.3noresultsvaluableinsupportingoneÕsthesis.Solutionssubmittedcontainedawidevarietyofapproaches,includinggraphtheoryandfuzzylogic.Unfortunately,severalteamswereconfusedastotheexactproblemthatthedeanwantedsolved.Assigningstudentstodeciles,byitself,wasnottheproblem;forexample,decilescouldbeassignedfromanylistofstudentnamesbychoosingtheÞrst10%ofthestudentstobeintheÞrstdecile,etc.Thedeanwantedmeaningfuldeciles,basedonstudentsÕrelativecourseperformance.Simplyre-scalingGPAssothattheaveragebecamelower(andthetop10%becamemorespreadout)wouldnotchangetheinherentproblem.Theproblemstatementsuggestedthatrelativerankingsofstudentswithincoursesshouldbeusedtoevaluatestudentperformance.Withthisassumption,possibleapproachesinclude:

•usingrelativerankingwithgradeinformation(Ausefuladditionalassumptionmightbethatfacultywouldgivegradesbasedonanabsoluteconceptofwhatconstitutesmasteryofacourse.)

•usingrelativerankingwithoutgradeinformation

Inthelatterapproach(chosenbymostteams),aninstructorwhoassignsAstoallstudentsinacourseprovidesexactlythesameinformationasaninstructorwhoassignsallCstothesamestudentsinanothercourse.SpeciÞcitemsthatthejudgeslookedforinthepapersincluded:

•ReferencetorankingproblemsinotherÞeldsthatuserelativeperformanceresults,suchaschessandgolf.

•Adetailedworked-outexample,illustratingthemethod(s)proposed,eveniftherewereonly4studentsintheexample.

•Computationalresults(whenappropriate)andproperconsiderationoflargedatasets.Teamsthatusedonlyasmallsampleintheircomputationalanal-ysis(say20students)didnotappreciatemanyofthedifÞcultieswithimple-mentingagradeadjustmenttechnique.

•Mention(ifnotuse)ofthefactthateventhoughtheGPAmaynotbeasÒgoodÓadiscriminatorasthevarioussolutionsobtainedbytheteams,itseemsreasonablethattherebesomecorrelationbetweenthetwo.

•AresponseindicatingunderstandingofthequestionaboutthechangingofanindividualstudentÕsgrade.SuchagradechangecouldaffectthatstudentÕsranking,butifitaffectedmanyotherstudentsÕranksthenthemodelisprobablyunstable.

•Aclear,concise,complete,andmeaningfullistofassumptions.Neededassumptionsincluded:JudgeÕsCommentary325ÐTheaveragegradewasA−.(Thismustbeassumed,asitwasstatedintheproblemstatementÑamazingly,severalteamsassumedotherstartingaverages!)

Ðinan{A+,A,A−,...}system,notallgradeswereA−.(Otherwise,thereisnohopefordistinguishingstudentperformance.)

Manyteamsconfusedassumptionswiththeresultsthattheyweretryingtoobtain.Teamsalsomadeassumptionsthatwerenotusedintheirsolution,werenaive,orneededfurtherjustiÞcation.Forexample,

ÐManyteamsassumedacontinuousdistributionofgrades.Asanapprox-imationofadiscretedistribution,thisisÞne.However,severalteamsallowedgradeshigherthanA+,andotherteamsneglectedtoconverttoadiscreteonewhenactuallysimulatinggrades.

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Economy

Economy


The national economic system 国民经济体系 The comprehensive/overall national power/strength 综合国力 Per capita GNP (gross national product)人均 The total industrial and agricultural output value The economic growth rate 小康生活 To enjoy a fairly comfortable life/ a well-off life 小康社会A moderately prosperous life Achieve the modernization drive in an all-round manner全 面实现现代化 Lack vitality 缺乏活力bring vitality to
Diversified ownership 多种所有制 公有制/非Public/non-public ownership enterprise Insist on the primacy of public ownership Individual/private/socialist market economy 个体经济/私营经济 以公有制为主体的多种所有制Diversified ownership with the public ownership economy as the mainstay Give priority to the development of 优先发展 从国外引进先进的技术和管理知识 Introduce advanced technologies and management expertise from abroad Emancipate and develop productive forces
Business strategy and environment

Business strategy and environment


Learning Aims
• Assess the significance of the changes taking place in the ecological environment, and their impacts on human well-being • Analyse the diverse roles of the key stakeholders in resolving environmental dilemmas, particularly governments and consumers • Assess the new ‘business environment’ facing global businesses
Ethics and the Environment
2. Economic and Social Changes • Income growth • Changing consumption patterns • Increased social (and physical) mobility • Growing international trade in both agricultural and industrial products • Resultant increases in energy consumption, and resource depletion
Ethics and the Environment
• …bringing with it the build-up of greenhouse gases, and unpredictable weather patterns • Soil degradation now affects the livelihood of over 1b. people… • …while a further billion are affected by the global fisheries crisis • So that, such environmental degradation and pollution now threaten the improved well-being which economic development have brought about… • …and, thus questioning its ‘sustainability’
29_monetary_system

29_monetary_system


Copyright © 2004 South-Western
Twas created in 1914 after a series of bank failures convinced Congress that the United States needed a central bank to ensure the health of the nation’s banking system.
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Copyright©2003 Southwestern/Thomson Learning
CASE STUDY: Where Is All The Currency? • In 2001 there was about $580 billion of U.S. currency outstanding.
• The directors appoint the district president, which is approved by the Board of Governors.
Copyright © 2004 South-Western
The Federal Reserve System
Copyright©2003 Southwestern/Thomson Learning
Copyright © 2004 South-Western
The Functions of Money • Unit of Account
• A unit of account is the yardstick people use to post prices and record debts.
Copyright © 2004 South-Western
The Fed’s Organization • The Federal Open Market Committee (FOMC) is made up of the following voting members:
HND_经济学导论_outcome2_标答

HND_经济学导论_outcome2_标答

Outcome 21.书178，179二个图Households buy commodities from firms, using the income individuals receive for their labour and capital supplied to firmsThe firms use the income received from the sale of commodities to pay for the labour and to invest in new premises,plant and equipment.2.Injections：Investments：Loan from banks, building societies, insurance companies etc. Money saved by household can be re-injected back into the inner flow as investment by business sector (firms) after they borrow the money out of financial institutions. Government Spending：Roads, hospitals, ing the fund largely collected through taxation, the government can be the biggest buyer spending money on the products and services provided by firms If government wishes to expend the flow of income in circulation, it may choose to increase the amount of its spending and probably adopt a tax-cutting.Exports：These are goods and services that are sold abroad. The payment for them will return to the firms in this country. For example, if someone buys textiles of China, then the proceeds of the sale belong to our country. This increases the circular flow and creates more economic activity in the economy for our country. Withdraws：Savings：Amount of income that consumers choose not to spend but retain for the future uses (normally deposit in financial institutions, e.g. banks and buildingsociety). Ability or desire to save out of income is measured by ‘marginalpropensity to save (MPS)’. Level of income is the biggest factor affects level of savings, i.e. the higher the income is, the greater savings (withdrawal) out ofcircular.Taxation：Through forms as personal income tax, V AT, corporate income tax, the disposable money circulated in the economy is drawn out by the government as its revenue. This can be in the form of direct tax on our income or indirect tax onpurchases, for example V AT.Imports：Part of the consumption of both households and firms are on foreign products or products contain imported components. So that portion of expenditure will eventually go into foreigners’ pockets therefore reduce the total income circulatedin domestic economy. For example if someone in Britain buys a Japanese car, then the proceeds of the sale will go back to Japan. Imports are therefore withdraws from the circular flow.3.四选二(a)1.Production: In calculating GNP, only those items which are paid for are normally included because calculations have to be made in money terms, the inclusion of other goods and services would involve imputing a value to them. For example, if a value is placed on certain jobs which a person does for himself—growing vegetables, cleaning his car, painting his house, then why not include shaving, cooking, cleaning, driving to work, etc. on the other hand, excluding what a person does for himself may distort national income figures. An imputed money value is included for certa in payments in kind which are recognized as a regular part of a person’s incoming earning, for example, goods produced and consumed by a farmer.2,Danger of Double Counting:This can arise through ‘stock appreciation’. When inflation occurs, the value of stocks of raw materials goods raises. While this adds to the profits of firms holding such stocks it represents no increase in real output. Such gains therefore, must be deducted from the Income and Output figures.3,The Black Economy: The size of the black economy can be difficult to estimate but certainly causes distortion. National Income figures for certain industries, for example, building industries have many workers who are self-employed and are paid in cash, tax revenue is lost and welfare benefits are claimed unnecessarily.(c)National Income will be in equilibrium when expenditure is equal to consumption or when injections equal total withdrawals total. And change in the level of injection or withdrawals will bring about a change in National Income. However, the change in National Income will be relatively greater than the initial change. This is known as the “Multiplier” effect.+ 书第200页的公式。