Twitter and Nielsen have joined forces on a new industry-standard metric called Nielsen Twitter TV Rating. It’s based completely on Twitter data.

The multi-year agreement enables Twitter and Nielsen to offer the new metric for commercial availability starting next fall.

“As the experience of TV viewing continues to evolve, our TV partners have consistently asked for one common benchmark from which to measure the engagement of their programming,” says Twitter Head of Media, Chole Sladden. “This new metric is intended to answer that request, and to act as a complement and companion to the Nielsen TV rating.”

“The Nielsen Twitter TV Rating is a significant step forward for the industry, particularly as programmers develop increasingly captivating live TV and new second-screen experiences, and advertisers create integrated ad campaigns that combine paid and earned media,” said Steve Hasker, President, Global Media Products and Advertiser Solutions at Nielsen. “As a media measurement leader we recognize that Twitter is the preeminent source of real-time television engagement data.”

“Ultimately, we have one goal for this new metric: to make watching TV with Twitter even better for you, the TV fan,” says Sladden.

The metric will complement Nielsen’s existing TV ratings. The companies say that the Nielsen Twitter TV Rating will give advertisers “the real-time metrics required to understand TV audience social activity”.