• Los Angeles Times, Wednesday, August 24, 2011 12:45 PM

Steve Carney provides a detailed account of how Arbitron's Portable People Meters (PPMs) have not only changed radio ratings but radio programming itself.

In addition to format changes, the change to instant measurement from the diary method -- which relied on listeners' memories -- has resulted in the end of such practices as incessant repetition of station call letters, and promotions timed to reach a crescendo just before the end of diary periods.

The PPMs may also have led to the playing of less new music -- because now Arbitron knows when someone hears the first notes of a song and changes the station.

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