The Miami-Dade (Fla.) County Board of Supervisors is the latest entity to take on Arbitron’s Portable People Meters. On Tuesday the board adopted a resolution to “ensure that the ratings methodology used by the Portable People Meter ratings system designed to measure radio station listenership does not under-represent minority radio listeners.” That’s the alleged problem that is drawing so much attention to the ratings devices. Broadcasting & Cable also reports that the House Oversight and Government Reform Committee plans to investigate the devices. In its defense, Arbitron contends it has been refining and improving the meters with suggestions from members of Congress, the FCC, the industry and other interested parties. The FCC began an investigation (PDF) into the PPMs last month.