The MRC said it made the decision based on audit results for PPM ratings in 2011, which revealed issues with “internal controls” of the service and declines in service performance metrics.

The move affects ratings in Cleveland, Portland, Riverside-San Bernardino, Salt Lake City and Tampa. It leaves just nine markets where PPM has MRC accreditation, out of 48 where it operates.

MRC chief George Ivie said: “Arbitron has committed to continue to work with us in the MRC’s ongoing audit and accreditation process for the PPM service, and we will continue to monitor and evaluate their progress as they try to reach this goal. We look forward to a time when these and the other unaccredited PPM markets can receive MRC accreditation.”

Arbitron’s executive vice president for service innovation and chief research officer Gregg Lindner said: “Consistent with our long-standing priorities, we will work to retain accreditation where we have it, to regain accreditation where it was withdrawn and to achieve accreditation in our remaining PPM markets.”