The study, to be released on Tuesday, examined Twitter chatter and minute-by-minute Nielsen ratings of 221 episodes of prime-time shows on major networks. Most of the time, there was no statistically significant relationship between the two sets of data. But Twitter messages were shown to cause a “significant increase” in ratings 29 percent of the time, said Mike Hess, an executive vice president at Nielsen and the senior researcher involved in the study.

A casual connection was also shown in the other direction as well: that is, the ratings had an impact in the volume of related tweets 48 percent of the time. Some genres of shows were much more likely to benefit from Twitter conversation than others.

“Over all, this does validate that additional research around this influence is worth pursuing,” Mr. Hess said.

Nielsen and Twitter are business partners — they are promoting a new metric called a Nielsen Twitter TV Rating that measures online conversations about shows — so the study may provoke some skepticism. Its findings, though, are likely to be cheered by networks and marketing firms that have invested heavily in social media. Anecdotes about spikes in the ratings credited to Twitter chatter have given producers and advertisers new hopes of assembling mass audiences.

Mitchell J. Lovett, a professor at the University of Rochester who has studied Twitter-television correlations, said that demonstrating causality had proved difficult in the past.

“It is hard to distinguish whether Twitter (or other social media) activity simply reflects existing interest (the person talks about the show because of an interest in watching or plans to watch) rather than causes it,” he wrote via e-mail. For that reason, the Nielsen study “could be groundbreaking,” he said, though he cautioned that he had not examined its methodology yet.