Arbitron Wednesday began rolling its portable people meter service out in Philadelphia. Philadelphia, which was Arbitron's first test market for the portable metering devices, is its second commercial
market for the new service, following Houston, which was rolled out earlier this year. Four Philadelphia-area broadcasters, which own 14 stations, have signed on for PPM results, and a number of
national media agencies have also contracted for the service. Arbitron has recruited 2,040 individuals to carry the PPM in the Philadelphia area.