aaronread said:
the objective PPM vs. the subjective diaries.
We need to be careful about throwing around the word "objective" here. Fact is, NEITHER of these measurement methods are "objective," because neither of them measure actual listening impact. PPM measures exposure and diaries measure recall. If a non-Spanish-speaking person has a PPM and sits in a taxi being driven by a Hispanic person, who is listening to a Spanish-language station, the PPM will record the time spent exposed to the Spanish-language station...but no impression has been made upon the listener, who doesn't understand the language. Similarly, if a diary keeper sits in a doctor's waiting room that has a radio station on at very low volume, it's likely that listening won't be recorded in the diary.
Until Arbitron comes up with the ultimate method to record impressions (a brain implant), they still have no way of measuring a station's (or, more to the point, an advertiser's) impact on the listener. The only advantage PPM has over diaries is that it skirts the issue of relying on imperfect human memory.