The firm said it would not disclose the identity of any panel members, but confirmed that the diaries were obtained from a “media-affiliated household” and were for the Week 3 period.

Information from the seven diaries has been deleted and Arbitron will reissue ratings data for the market tomorrow.

The firm said: “Audience estimates for [local sports broadcaster] WQYK-AM may be substantially affected. Estimates for other stations recorded in the deleted diaries may be affected to a limited degree in select demos and dayparts. In addition, stations that did not receive listening in the deleted diaries may be slightly affected as a result of sample balancing and reprocessing procedures that accompany deletion of any diary from the sample.”

Last month Arbitron announced it was reissuing four months’ worth of ratings data for the New York market after a data entry error.