How are audience impressions determined?

[Acid Eyes]

How do radio stations determine how large their audiences are? Can they track their audience whether someone turns on a radio? Or is it measured somehow once a year and then adjusted later on?

If impressions are monitored the second you turn on a radio, does it matter how long you listen to a song? Does one second equal three minutes in this case?

If they are not determined automatically, is there some sort of census that determined the audience?

And just as a side question, are TV ratings determined the same way?

[EvanJ]

I guess you could call the Arbitron radio station ratings a census. It's a sample. 98 radio markets are constantly monitored and have ratings released to the public once a month if the market is not made client exclusive by Arbitron. The rest of the about 300 radio markets are not constantly monitored, with a fall and a spring quarterly rating released every year. As for you listening to a song for 1 second vs. 3 minutes, one term in Arbitron ratings is average quarter hour (AQH). Arbitron is currently in the process of at least for some markets changing from the diary system, in which the listeners sampled record and submit what stations they listened to and for how long, to the electronic Portable People Meter (PPM). One problem I read about the PPM (something small you wear) is that if a listener being sampled is in a place such as work where he or she does not control what radio station is on and may not like station, what the PPM records does not match what stations the person what like to listen to. As for how radio station ratings translates into audience on the charts, I don't know if you will ever get a good answer to that unless you work in the industry.
You can try registering on the radio-info or radioinsight message boards and asking for more information.

[mst3k]

evanj said:

As for how radio station ratings translates into audience on the charts, I don't know if you will ever get a good answer to that unless you work in the industry.

Can't be that much of a mystery. The ratings basically give you an estimate of how many listeners a station has in any given time period (I think BDS breaks the day into four or six dayparts for audience purposes). So based on what time period each song is played, it's easy enough for BDS to calculate how many people are (supposedly) hearing it. Total it up for a week and there you go.