Ratings Glossary

We all use ratings information, but it's baffling to me how few users even understand how the metrics are derived. On a day-to-day basis I can honestly say it doesn't matter for most users. Like the speedometer in your car, it is usually enough to know what do do with the data. But there is a downside to ignorance. As a consequence, most of radioland was nonplussed by the legal challenges to PPM. Some of them did have merit, but PPM is undeniably superior to the system it replaces.The problem wasn't that Arbitron faced a possible rebuke. The problem was that the user base was so uninformed as to be unable to take a side.

Take for example the lawsuit Arbitron just settled a in California on March 21st.  Arbitron was taken to task for using land lines for recruiting respondents for their sample. Minority households are known to be statistically less likely to have a land line. Many users of Arbitron measurement data didn't know if this was a benefit or a detriment to them.  Personally I believe that accuracy is a benefit to all users, but I also understand the argument in favor of advantageous bias. It was the state of California itself that brought the suit, no radio stations were specifically named. More here and here.

In fairness I can hardly blame Arbitron. some of the nuance requires a degree in statistics. While the company has some serious, short-comings, namely their delivery method: CD-R via Fed-Ex one market at a time!... They do make an honest effort to disclose their terminology in a fairly straight forward way. Below I quote and elaborate on their basic terms and acronyms. All users should understand everything below. If you don't, you need to call your rep on Monday.  Don't be embarrassed. If you are paying for this data, make it worth your money. More here.

AQH
Average Quarter-Hour: a 15-minute period

Average Quarter-Hour Persons (AQH Persons)
The average number of persons listening to a particular station for at least five minutes during a 15-minute period.

Average Quarter-Hour Rating (AQH Rating)
The AQH Persons estimate expressed as a percentage of the population being measured. This estimate is printed for the MSA and DMA. It can also be computed for the TSA.
[AQH Persons / PUR] x 100 = AQH Rating (%)

Cume Persons
The total number of different persons who tune to a radio station during the course of a daypart for at least five minutes.

Cume Rating
The Cume Persons audience expressed as a percentage of all persons estimated to be in the specified demographic group. [Cume Persons / PUR] x 100 = Cume Rating (%)

Daypart
A time period for which audience metrics are reported. In radio we use divide up the 24-hour day  in to segments. These are for scheduling advertisements, but also as a way to easily divide up ratings data. The below only applies to weekdays. More here.
AM Drive: 6:00 AM to 10:00 AM
Midday: 10:00 AM  to 3:00PM
PM Drive: 3:00 PM to 7:00 PM
Evening: 7:00 PM to 12:00 PM
Overnight: 12:00 PM to 6:00 AM

PUR
Persons Using Radio. This is described in some documentation as "population."  This is somewhat misleading as it's actually just the subset of the population using radio.

Rating (AQH or Cume)
The audience expressed as a percentage of the total population.
[Listeners / Population] x 100 = Rating (%)

Reach
The total number of unique individuals exposed to a song or ad in a given daypart. Reach can be calculated for a single station or multiple stations.

Share
The percentage of those listening to a single radio in a given Metro who are listening to a particular radio station. [AQH Persons to a Station / AQH Persons to All Stations] x 100 = Share (%)

TSL
Time Spend Listening: The amount of time the average listener spent listening to a radio station during a daypart. The estimate may be expressed in number of quarter hours or in hours/minutes.