Rentrak said that Zenith Media has become the first national agency to pick Rentrak’s local TV data as the basis for planning and buying local TV advertising.

Rentrak has been providing ratings information on viewing for a growing number of stations, supplanting Nielsen in the local ratings business.

While Nielsen’s data is mainly based on panels of sample viewers, Rentrak primarily relies on viewing information that comes from millions of set-top boxes.

Read more at B&Chere.