analyzing minute-to-minute trends in Nielsen’s live TV ratings and tweets for 221 broadcast primetime program episodes using Nielsen’s SocialGuide, the study found that live TV ratings had a meaningful impact in related tweets among 48 percent of the episodes sampled. The results also showed that the volume of tweets caused significant changes in live TV ratings among 29 percent of the episodes.
The study also found that the impact of Tweets varied across program genres. The impact was greatest for competitive reality shows (no surprise there), and also found that Twitter impact was greater for comedies than sports programs (a bit of a surprise). Drama was least affected by concurrent Tweeting.
Source - The Follow-Back: Understanding the two-way causal influence between Twitter activity and TV Viewership, Nielsen newswire