By Paul Farhi
Washington Post Staff Writer
Saturday, March 7, 2009; Page C01
... Arbitron, the radio industry's dominant audience-measurement company, has never publicly released a national estimate for Limbaugh, and it says, in effect, that the job is too complicated, expensive and time-consuming to bother with.
The difficulty comes from the vast patchwork that is Limbaugh's radio empire. His three-hour daily program is carried on more than 600 domestic stations, but these stations don't all carry the show at the same time or even for the same duration. Most air all three hours of Limbaugh's broadcast each weekday, but some carry only two hours. Arbitron has never attempted to aggregate all of this audience data for this many stations and times. "There is no economic motivation for any objective third party to do that kind of analysis," says Thom Mocarsky, an Arbitron spokesman ...
The ratings service can say with some precision how large Limbaugh's audience is in a particular city and at a particular time. In the Washington region, for example, Limbaugh's program -- carried from noon to 3 p.m. on WMAL (630 AM) -- attracted an average of 167,700 unique listeners per week during January. Limbaugh has never been a huge draw in Washington; his show ranked 14th overall during January, far behind ratings leaders WTOP-FM (567,500 weekly listeners), soft-rock station WASH-FM (526,300) and Top-40 station WIHT-FM (349,300).
Premiere Radio Networks, Limbaugh's national syndicator, estimated last year that 3.59 million people were in Limbaugh's audience during an average quarter-hour of his program, based on a review of Arbitron's piecemeal data about hundreds of stations ...
http://www.washingtonpost.com/wp-dyn/content/article/2009/03/06/AR2009030603435.html?hpid=topnews