Yep, Spit has it right. Arbitron’s home page can give you more details. They do show a handheld device like a pager that can also be used, but diarykeeping by selected responders is the standard.
Of course, radio stations hate the whole process, because self-reporting is far from accurate. Many diaries are filled out later, after the fact, and the responders are much more likely to report what they feel is cool than what they actually listen to.
In the larger markets, a “book” is taken every quarter. In order to use the statistics from that book to sell your radio station, you have to buy the rights from the friendly Arbitron folks.
The books are highly complex, breaking out into market demographics, dayparts, “cumes”, “AQH
(average quarter hour)” etc. No matter how pathetic a station scores, it is almost always possible to find a number or two the sales staff can massage into a pitch. “Hey, we’re in the top third of stations in the market from midnight to 6 a.m. for 12-17 year old females who own their own homes!”
Careers of all sorts are made or broken by the books.Your favorite DJ may be loved by management, and an all-around good person, but a bad book (or, more likely, two bad books back-to-back) for the daypart in which they’re on the air, and they may be sending out airchecks in a hurry.
In the smaller market, on the other hand, surveys are not conducted until some station thinks they have enough clout to look really good. Then they will commission a survey. The survey company will then pitch the other stations in the market to see if they want to buy the rights to use the survey as well. That happened to a station I worked for in the early 80’s. Station A commissioned the survey, and we looked good enough in a number of areas, that we bought it as well. And, as sales manager, I was able to say, “Hey, KXXX commissioned the survey, not us. But the survey company thought we might be interested after they saw the results, and they were right.” It gave a hey-these-aren’t-our-numbers, but-don’t-they-look-good? cachet that helped a great deal.
All the above may be TMI – don’t ever ask a radio person about surveys.