Arbitron Promises More Stability In PPM Radio Ratings

From Mel Phillips Now And Then Blog...

There are just too many bounces in PPM (Portable People Meter) radio numbers.

For years radio has depended on consistency when being measured but it's not always getting it now with far too many spikes from rating period to rating period. Arbitron is determined to eliminate those bounces with new company rules. Under existing rules, almost 20% of a market's PPM panel could turn over during a three-month period, causing wide rating swings from month-to-month but that's about to change, according to Arbitron. Starting with the November survey, Arbitron will use new sample expiration rules intended to smooth out the turnover...

Arbitron's new rules are expected to be applied in all PPM markets by March, 2011. All initially selected samples will expire between 18 and 30 months under the new rules as opposed to expiring between 18 months and 36 months under the current plan with the maximum panel tenure after the initial build period set at 24 months. "Once we've spread out that turnover from the initially selected sample, ongoing sample will expire between 18 and 24 months, so we'll continue to smooth out the turnover" Arbitron's Beth Webb says. "You won't get a three-month period where there's a huge turnover in the panel. this will help the stability of the estimates in that period."

Arbitron's old rules "were creating a spike in turnover right around 24 months after a panel was filled. As we improved compliance, people were staying in the panel longer." Webb adds that many were remaining for the full 24 months after the sample build, resulting in a large number being replaced simultaneously, creating a lot of turnover in the panel all at once, which creates increased variance in the estimates." That should all end now under the new Arbitron rules...

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