统计(Statistics)

thereweretwowidelydivergentinfluencesontheearlydevelopmentofstatisticalmethods.statisticshadamotherwhowasdedicatedtokeepingorderlyrecordsofgovernmentunits(statesandstatisticscomefromthesamelatinrootstatus)andagentlemanlygamblingfatherwhoreliedonmathematicstoincreasehisskillatplayingtheoddsingamesofchance.

theinfluenceofthemotherontheoffspring,statistics,isrepresentedbycounting,measuring,describing,tabulating,ordering,andthetakingofcensuses-allofwhichledtomoderndescriptivestatistics.fromtheinfluenceofthefathercamemoderninferentialstatistics,whichisbasedsquarelyontheoriesofprobability.

describingcollectionsinvolvestabulating,depictinganddescribingcollectionsofdata.thesedatamaybequantitativesuchasmeasuresofheight,intelligenceorgradelevel------variablesthatarecharacterizedbyanunderlyingcontinuum---orthedatamayrepresentqualitativevariables,suchassex,collegemajororpersonalitytype.

largemassesofdatamustgenerallyundergoaprocessofsummarizationorreductionbeforetheyarecomprehensible.descriptivestatisticsisatoolfordescribingorsummarizingorreducingtocomprehensibleformthepropertiesofanotherwiseunwieldymassofdata.

inferentialstatisticsisaformalizedbodyofmethodsforsolvinganotherclassofproblemsthatpresentgreatofproblemscharacteristicallyinvolvesattemptstomakepredictionsusingasampleofobservations.forexample,aschoolsuperintendentwishestodeterminetheproportionofchildreninalargeschoolsystemwhocometoschoolwithoutbreakfast,havebeenvaccinatedforflu,orwhatever.

havingalittleknowledgeofstatistics,thesuperintendentwouldknowthatitisunnecessaryandinefficienttoquestioneachchild:theproportionforthesampleofasfewas100children.thus,thepurposeofinferentialstatisticsistopredictorestimatecharacteristicsofapopulationfromaknowledgeofthecharacteristicsofonlyasampleofthepopulation.