Led by Judiciary Committee chairman John Conyers, the congressional representatives have written to acting head of the GAO Gene Dodaro (pictured) to request a study into claims made by minority broadcasters that their audiences are under-represented in PPM samples which is harming their ratings and advertising revenue.

The letter states: “While we understand that Arbitron is attempting to accurately account for all listenership, we want to ensure that the use of the PPM is in fact counting all populations accurately.”

Concerns over PPM measurement were raised at a Judiciary Committee hearing earlier this month on trends affecting minority broadcast ownership. Before that, the House Oversight and Government Reform Committee had opened its own inquiry into the issue.

Edolphus Towns, chairman of the Oversight Committee, has also signed the letter calling on the GAO to investigate – though it seems unlikely Dodaro will grant the representatives’ request.

Similar demands were made of what was then known as the General Accounting Office in 2004, when Nielsen faced accusations that its new system of measuring local TV audiences was undercounting viewership of minority stations.

The GAO declined to intervene, saying it had no legal basis to do so as its remit is restricted to examining uses of public funds.

However in their letter the congressman argue that a review of Arbitron’s methodology “is an appropriate task for the GAO” because certain federal agencies, such as the Federal Communications Commission (FCC), rely on Arbitron data “in developing and implementing its regulations”. The FCC is holding its own inquiry into the reliability of PPM data.

In response to calls for a GAO investigation, Arbitron said: “As always, Arbitron welcomes every opportunity to discuss the PPM technology, service and our sampling methodology. We continue to have a dialogue with key members of Congress as well as other interested parties, and look forward to helping the radio industry as a whole remain competitive in the current media marketplace.”