Later next year the new electronic method of tracking terrestrial radio listeners debuts in New York City. Until then, New York City -- market 1 -- is still using the quarterly Arbitron paper diary method. In markets where monthly electronic ratings are already being used -- like Houston and Philadelphia -- it is changing basic assumptions of radio. From Seth Seutel of AP:

''Chris Caldwell, a media buyer at the Houston-based agency Briggs & Caldwell, says that the 'morning drive' time slot isn't as highly rated under the electronic system as it was before, and weekend listening is much stronger than most people believed.

'''Our radio budget hasn't changed, but the way we disperse that radio budget has,' Caldwell said.''

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