Some 10 months after signing an exclusive partnership deal with Twitter, Nielsen has launched its TV ratings system for the social media giant.

The Nielsen Co. 's new measurement index for Twitter Inc. tracks the volume of tweets generated by different television shows in the US. It also tracks the number of unique authors posting TV-specific tweets and provides information about the audience of Twitter users viewing tweets about each program.

To mark the launch, Nielsen has begun releasing a weekly top 10 list of the most popular shows on Twitter. For the week of October 3, the TV show Scandal won by a landslide for number of tweets generated and overall audience impressions. Miley: The Movement and Saturday Night Live came in a distant second and third, respectively, although both shows were closer to meeting Scandal's numbers as measured by size of the unique Twitter audience reached.

The pairing of Twitter and TV is big business. With the new service, Nielsen is trying to make the most of its acquisition of SocialGuide last November, as well as its exclusive deal with Twitter. (See Nielsen Tests Tool to Track TV Everywhere.)

Twitter participation is still limited in the US, but it continues to grow. While less than 20 percent of online adults in the country use Twitter according to the Pew Research Center, Nielsen notes that "19 million unique people in the US composed 263 million Tweets about live TV in Q2 2013 alone, a 24 percent year-over-year increase in authors and a 38 percent increase in Tweet volume."

Meanwhile, Twitter isn't the only data set that programmers and advertisers are using to supplement Nielsen's traditional TV ratings numbers. Set-top data has also emerged as a leading source of information on TV viewing behavior. Some cable companies license set-top data to third parties, while others use it primarily for their own advertising sales. (See Cable Embraces Big Data.)

— Mari Silbey, special to Light Reading Cable