ABSTRACT
A short consideration of the corporate structure of American commercial broadcasting will make us comprehend more fully why the practice of audience measurement has acquired the central role it has been occupying almost from its inception. In economic terms, production for profit is the sole objective of the commercial broadcasting industry, which has for decades been dominated by the three national networks, NBC, CBS and ABC. To finance the whole system, the networks are dependent on advertisers as sponsors. The idea of advertising is principally based upon the assumption that it is possible to enlarge sales of products through communication.1 It is the prospect of fusing selling and communicating that induces interest on the part of advertisers to make use of television or radio to disseminate their promotional messages. Therefore, a system has emerged in which advertisers buy air time from the broadcasters, either fifteen-or thirtyor sixty-second spots, to be inserted in programmes that are furnished by the networks.2
