I know TV has the Nielsen box, but as far as I know, there is no equivalent device for radios. A friend of my used to work for a college radio channel and he said all they do is survey people, but that seems inaccurate and time consuming to do with a large national broadcast
Here is some information by market… http://www.radioandrecords.com/RRRatings/DefaultSearch.aspx?ShowAll=yes
I believe the largest national radio ratings firm is Arbitron. Historically they’ve relied on rather low-tech self-reporting — people write down what they’ve been listening to in a journal and mail it back to them. This is fraught with inaccuracies, since people don’t always realize that they’re listening to a radio station (in a waiting room, say), they don’t remember to write down listening periods soon after they occur, and if they try to reconstruct their listening “right before it’s due”, their recollections can be inaccurate. (Quick, at what times did you listen to the radio on Tuesday?)
Arbitron has recently been trying out a new device, the Portable People Meter, which clips on to your belt and listens for special codes embedded in radio broadcasts. This method should be more accurate, but I don’t believe they’ve fully moved over to this system yet.
(As a perhaps-not-GQ-appropriate aside: the PPM also seems vaguely creepy & Orwellian to me. I suppose on some level it’s no worse than slavishly writing down all your listening habits; perhaps it’s the lack of control that the subject over the data he or she submits has that bugs me.)
Arbitron also assumes that you’re being honest about what you’re listening to. Listening to the morning shock jock and reporting NPR doesn’t really help either station, since the shock-jock’s station is deprived of ratings points and public broadcasting isn’t measured in the same way.
Some stations do surveys by telephone in order to get feedback on programming to get a better sense of what listeners actually want to hear (or don’t want to hear) versus what the programming director thinks they want to hear. In fact, Dave Barry got a book out of it after such a survey resulted in a column that led to the book. These surveys aren’t the same as the Arbitron surveys, however.
Just wanted to say I was an Arbitron survey person in 2006. It really is that low tech. They just sent me a paper diary and told me to write in what I listened to. There wasn’t even an attempt to try to validate my entries and for that matter who I was.
The phone surveys aren’t much better. I also participated in a phone survey that year. They give you ten second snippets of songs and ask you to rate them 10 to 1. Since a song isn’t going to be recognized unless it got played a lot, it’s pretty much useless on judging brand new songs.