Same with ratings data. So long as rating estimates are not the sole reason for making decisions, or the only benefit a station can present to a potential sponsor, then they are well worth the money invested. It is when the tail wags the dog -- when everything we do, every decision we make, is to try to squeeze out another tenth of a share point--that we get into trouble.
I posit that is part of the angst with PPM, Arbitron's new methodology for gathering audience info using data encoding on transmitted signals measured by devices hanging on recruited panel members. (Disclaimer: I was an executive with Arbitron during the early development of this technology and am convinced it is the best method yet for measuring radio listening.) It is more and more difficult for radio stations to "game" the numbers. PPM carriers are listening or they are not. No rubber clocks (giving incorrect time so diarykeepers would write down longer periods of listening) or hyped contests all aimed at getting diarykeepers to write down our station, whether they are listening or not.
I still cringe when I hear about stations interfacing music scheduling software with PPM data and making major song choices based on a precious few "meters" who "tune out" during the song. Or using dangerously narrow demo/daypart/geo data to make crucial choices in programming and personnel.
The ability to get near-immediate multi-media single-source listening data that is gathered as impassively as PPM does is a wonderful thing. The danger of reading too much into those data could be another nail in the coffin of a medium we all love so much.