postmaster@CUVMB.CC.COLUMBIA.EDU (02/23/90)
I've always wondered how a radio station (shortwave, or local AM/FM) determines the size of its listening audience. I guess the amount of mail received is one indication (one needs to then assume some proportion of the listeners typically send mail...e.g., 1%) but how reliable can that be? I've assumed that local stations may hire some pollster to do some survey of people in the listening area, but can that work for shortwave stations? Anyone out there know the facts? - Jim Liuzzo
99700000 <haynes@UCSCC.UCSC.EDU> (02/24/90)
I believe it's done by calculation, at least for local AM/FM stations.
Given the transmitter power and the antenna characteristics you can
calculate zones of signal strength about the station. You can correct
the calculations by making field strength measurements in the field (no
pun intended). You can draw these on a map - for AM you have to have
separate day and night calculations if the station operates at night.
I remember seeing in a small-town newspaper, when the local AM station
was going for a power increase, a map of "before" and "after" coverage
within which the signal is strong enough to be easy to listen to.
>From that point you can count the houses on the map and estimate the
number of people per household, etc.
That takes care of the simple case out in the boondocks where there is
only one local station. For urban areas I guess they have to estimate
the percent of population listening to each available stations by some
other process.Tim Pozar <@UCBVAX.BERKELEY.EDU:pozar@hoptoad> (02/28/90)
In article <13233@cbnewse.ATT.COM> liuzzo@cbnewse.ATT.COM (james.g.liuzzo) writes: >I've always wondered how a radio station (shortwave, or local AM/FM) >determines the size of its listening audience. I guess the amount of mail >received is one indication (one needs to then assume some proportion of the >listeners typically send mail...e.g., 1%) but how reliable can that be? >I've assumed that local stations may hire some pollster to do some survey >of people in the listening area, but can that work for shortwave stations? >Anyone out there know the facts? Listening audience is gaged by a companies like Birch or Arbitron. Birch will call households and ask "What station are you listening to?" Arbitron will send out 'Diaries' for participats to fill out throughout the day. Arbitron puts out their results once every three months in "The Book". Stations live and die by this tabulation. If you get a bit rushed about seeing how you are doing, you can subscribe to "Arbitrends". Arbitrends (or the "Trends") are progress reports that come out every month. The "Book" is made up of Trends that are averaged and Ethnic weighted. Books and Trends will also give information broken down into "Dayparts". Or how many is listening during certain hours like 6a to 10a, or 3p to 7p, ect., and what age groups or gender. The Book will give more detail as in how listeners broken down into cities. How much you can ask for a commercial is directly related to your ranking in the Book. Most National buyers (large corperations) will not even look at a station that is not in the top 10. Tim -- Tim Pozar Try also... Internet: pozar@toad.com Fido: 1:125/555 PaBell: (415) 788-3904 USNail: KKSF / 77 Maiden Lane / San Francisco CA 94108