ComScore isn’t the only ratings service that can use precise data from set top boxes, as opposed to audiences surveys and samples, to count TV viewers. Nielsen today said it has a “multi-year agreement” with Dish Network to tap information from its set top boxes.

The Dish info is “the first nationwide dataset to be integrated with our panel data, reaching the perfect balance of deep viewing characteristics and the granularity of large datasets,” says Nielsen’s COO Steve Hasker. “As the global leader in audience measurement, this is another step in our efforts to integrate big data into our portfolio and our Total Audience efforts.”

Set top box data is especially helpful in small markets where the sample sizes for Nielsen’s surveys often are too small to give advertisers a clear sense of what niches of viewers watch.

So it’s not surprising that Nielsen will begin by blending the Dish data into reports for all 210 markets in its its Local TV Measurement service.  The ratings company also will use the results in other products including Nielsen Scarborough, Nielsen Data Fusion, and Nielsen Media Custom Insights.

Among other things, the information will help to determine marketing effectiveness, and return on ad sales for major buyers in consumer packaged goods, retail, and auto.

“This will allow advertisers and networks to improve their marketing and programming decisions even as television viewing itself becomes more fragmented.” says Warren Schlichting, Dish’s EVP of Marketing, Programming and Media Sales.

Although Nielsen has a firm grip on the national ratings business, ComScore, which bought Rentrak in February, has cited its access to set top box data as a competitive advantage for broadcasters and advertisers looking to improve local sales.

Pivitol Research Group’s Brian Wieser calls the announcement “incrementally positive” for Nielsen. Dish “arguably has the best national footprint among originating [pay TV distributors] who supply data” and “previously supplied its data exclusively to ComScore.”