Estimating the Impact of Advertising Media Plans: Media Executives Describe Weighting and Timing Factors

Advertising theory and practice require that media plans be developed and evaluated in terms of advertising exposures, or other desired communication effects, rather than media vehicle exposures. This often means that, when evaluating media schedules in terms of effective reach, for example, media vehicle audience ratings must be weighted. Also, optimum levels of message frequency typically must be feasible within an appropriate time frame. This article focuses on how leading advertising agencies implement theoretical constructs concerning effective reach when evaluating media plans. Media executives from 91 leading advertising agencies describe their agencies' procedures for weighting audience ratings, including the magnitude of weights typically applied to vehicle audience estimates in major media categories. Alternative definitions of effective reach and rationale supporting the use of various time intervals for media plan evaluation are also presented.