【英语翻译1.Reachandfrequency.Advertisersmustchoosesomecombinationofreachandfrequencytoattaintheiradvertisingobjectives.Reachisdefinedasthenumberofindividualsorhouseholdsexposedtoatleastoneadduringagivenperiodoft】

　　英语翻译

　　1.Reachandfrequency.

　　Advertisersmustchoosesomecombinationofreachandfrequencytoattaintheir

　　advertisingobjectives.Reachisdefinedasthenumberofindividualsorhouseholdsexposedtoatleastoneadduringagivenperiodoftime—typicallyfourweeks.Thetermcanbeusedinconnectionwithasinglemediavehicleoramediaschedulecomprisinganumberofdifferentmediavehicles.Reachistypicallyexpressedasapercentofthetargetaudience:forexample,ifthetargetaudiencewas100.000personsandthemediaschedulereached70.000,thereachwouldbe70percent.Ordinarily,costsriseatanincreasingrateashigherlevelsofreacharesought.

　　Duplicationoccurswheneveramarketerpurchasesasecondmedium.someportionoftheaudienceofthefirstmediumisalmostalwayspartoftheaudienceofthesecondmedium.AssumethatmediumAhasanaudienceof100.000personsandmediumB,90.000,if40.000ofthepersonsexposedtomediumBarealsomembersofA’saudience,thenbuyingthetwomediayieldsanunduplicatedaudienceof150.000---not190.000,duplicationleadstofrequency,whichisthenumberoftimesthetargetaudienceisexposedtoamessagewithinagiventomeperiod---usuallyfourweeks.

　　Thereareseveralproblemsinusingthesemeasures.Firstisthematterofdefiningthetargetaudienceandcorrelatingitwiththeaudiencesreachedbythevariousmediavehicles.Asecondproblemisdefiningexposure---isitanopportunitytobeexposedtoagivenmessageorisitanactualreadingofaprintad,actualwatchingofaTVcommercial,oractuallisteningtoanadinradio?Needlesstosay,itisadifficulttasktomeasureexposurenomatterhowitisdefined.Third,notallwhoareexposedareofequalvaluetotheadvertiser----somemaynotevenbeprospects.Fourth,howshouldsuccessiveexposuresbeweighted?Isasecondexposureworthmorethanathird?Andhowmuchtimeshouldelapsebetweenexposures?

　　Reachandfrequencymeasuresateusedtopreparetheadvertisingschedule,which,inturn,determinestotaladvertisingexpenditures.Inestimatingthecostofagivenschedule,mediaplannerssimplifytheirtaskbyusinggrossratingpoints,whichatecalculatedbymultiplyingreachbyaveragefrequency.Assumeareachof70percentan