大学英语六级阅读晨读美文分享 英语四六级

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Thereweretwowidelydivergentinfluencesontheearlydevelopmentofstatisticalmethods.Statisticshadamotherwhowasdedicatedtokeepingorderlyrecordsofgovernmentalunits(stateandstatisticscomefromthesameLatinrootstatus)andagentlemanlygamblingfatherwhoreliedonmathematicstoincreasehisskillatplayingtheoddsingamesofchance.Theinfluenceofthemotherontheoffspring,statistics,isrepresentedbycounting,

measuring,describing,tabulating,ordering,andthetakingofcensuses--allofwhichledtomoderndescriptivestatistics.Fromtheinfluenceofthefathercamemoderninferentialstatistics,whichisbasedsquarelyontheoriesofprobability.Descriptivestatisticsinvolvestabulating,depictinganddescribingcollectionsofdata.Thesedatamaybequantitativesuchasmeasuresofheight,intelligenceorgradelevel--variablesthatarecharacterizedbyanunderlyingcontinuum--orthedatamayrepresentqualitativevariables,

suchassex,collegemajororpersonalitytype.Largemassesofdatamustgenerallyundergoaprocessofsummarizationorreductionbeforetheyarecomprehensible.Descriptivestatisticsisatoolfordescribingorsummarizingorreducingtocomprehensibleformthepropertiesofanotherwiseunwieldymassofdata.Inferentialstatisticsisaformalizedbodyofmethodsforsolvinganotherclassofproblemsthatpresentgreatdifficultiesfortheunaidedhumanmind.Thisgeneralclassofproblemscharacteristicallyinvolveattemptstomakepredictionsusingasampleofobservations.

Forexample,aschoolsuperintendentwishestodeterminetheproportionofchildreninalargeschoolsystemwhocometoschoolwithoutbreakfast,havebeenvaccinatedforflu,orwhatever.Havingalittleknowledgeofstatistics,thesuperintendentwouldknowthatitisunnecessaryandinefficienttoquestioneachchild:theproportionfortheentiredistrictcouldbeestimatedfairlyaccuratelyfromasampleofasfewas100children.Thus,thepurposeofinferentialstatisticsistopredictorestimatecharacteristicsofapopulationfromaknowledgeofthecharacteristicsofonlyasampleofthepopulation.