Re: Incorrect information regarding PPM
> > The station is encoded, not the specific content. the
> > encoder has no way of knowing what is on the air, just tht
>
> > it is inserting the station identificatin encoding. There
> is
> > an engineers' white paper on the Arbitron website that
> > explains it all.
>
> Yes that's what I thought. Perhaps you can explain this:
>
> One concern expressed by the advertising community is that
> while programming is encoded, commercials are not.
> Advertisers want to know that their spots were heard.
The article says, "One concern expressed by the advertising community is that while programming is encoded, commercials are not. Advertisers want to know that their spots were heard. There are other concerns, too. How do you measure bath, shower and other private listening? How will it measure traveling listeners, who are often high-income people who spend days and weeks away from home and their base station? What about other people spending nights away from home? Will minority audiences be appropriately represented?"
The intent of radio ratings is to determine whether a station is being heard, not the individual components of the station. The PPM system is based on the same premise as the diary... quarter hour average measurement, with usage of 5 minutes or over giving a station credit for a particular quarter hour.
The PPM does not measure second by second listening levels... or minute by minute. It takes multiple "detections" per minute and creates average listening figures for broader time periods.
Obviously, if someone sits thier meter on the counter while in the shower, it will detect a station if any is playing... even if the person in the shower is not listening clearly. This is the gray area of the PPM. But, compared with the diary, we get a much better read of instantaneous usage, not mental rounding that diarykeepers often engage in.
Since radio is mostly a local medium, it really does not matter that a few people may be away. In fact, the meter has a motion sensor. If it is not detecting movement, the panel member is taken out of the sample for as long as it takes to get them to carry again or to get them out of the panel. If you think of how many people this might affect, it is minuscule. Generally, people with that busy a schedule are a) atypical and, b) not going to accept being part of a panel anyway, so the point is moot.
The PPM panel is as close to a perfect proportional sample as you could get today. Every variable that they control for, such as ethnicity, language usage, age, sex, income level, etc., is represented perfectly in the panel. If someone drops out, an "equal" is put in instantly. So higher and lower income, ethnic groups, etc. are all represented in true proportion to their presence in the community.