Just as the human nervous system controls all human functional activity, so do ratings control every functional activity in the broadcast industry.
This chapter discusses many of the different ways in which audience data are used. Nonprofessionals, whose familiarity with rating numbers is largely confined to periodic press accounts of rankings of national commercial networks and programs, are usually surprised to learn what detailed behavioral knowledge audience ratings services provide.
Any discussion of ratings usage must be connected to a fundamental aspect of the broadcast media (radio, TV, cable)--the perishability of electronic communication. Once a program is aired, the audience and the potential commercial time it bears are gone forever, never to be regained. Like the airline seat, empty when the jet takes off, or the tickets still in the box office after Sunday's pro football game, these unsold units are down the drain--there's no chance for revenue recovery by stockpiling or sale pricing at a later date. This aspect of commercial broadcasting creates a situation where marketplace supply-and-demand factors are potent in determining pricing.
Buyers look for the best buy on the basis of criteria established for the product in question using conventional rating parameters. But the ratings by which buyers and programmers alike gauge their activities are only measurements of the past, not the future when the new programs and commercials run. Any given program under consideration is likely to have quite a different audience in November than it did in May (perhaps the last rating available) or in November last year. Changed competition, lead-in, seasonal factors, and long-range trends can all