That raises questions as to who is saying what in social media, where it’s easier to mask identity and harder to know the origin of themes and memes.

Campaigns “obviously” are trying to drive social media conversation, says Rainie, because they know those metrics are a factor “reporters, supporters and donors are now going to pay attention to — it’s a new metric the political community is anxious to exploit.”

“But at the same time, there are too many people doing it to think it’s all manufactured,” adds Rainie, co-author of the 2012 book “Networked: The New Social Operating System.”

“If you’ve watched your own Twitter stream or your own hashtags, you saw stuff that was institutionally affiliated, but it was probably overwhelmed by the amount of stuff that came from individuals.”

Rainie says that even if some tweets are the result of people responding to calls from “parties or partisans,” that doesn’t necessarily make them “any less authentic.” Social media are giving people who “have already picked a team” a way to articulate that choice and try to influence the election.

“These are new ways for citizens to pitch their voices into the fray. In the pre-Internet era, what could they do? They could stand on street corners, write angry letters to editors, and that was about it.”

A bigger concern to Rainie is the possibility of placing more value on social-media data than is warranted.

“Because it’s measured, people invest a lot of value in it that might not be there,” Rainie says. “For example, the composition of the social media sphere tends to be a little bit more liberal than conservative. So, the conversation you’re going to see on social media ... might skew a little bit more liberal.”

Rainie says it’s crucial to understand that social media “is not a representative sample of the whole public.”

Instead, “It’s a very distinct sub-population of a sub-population,” he explains. “Twitter users are 16 percent of the Internet. So, Twitter doesn’t even represent the whole Internet. And the people who talk about politics on Twitter are a subset of Twitter — not everybody talks about politics.”

What appears on Twitter “shouldn’t be seen as the sum total of how people are reacting to the debate and how they’re thinking about voting,” he says. “As my colleague, Tom Rosenstiel at the Pew Project for Excellence in Journalism, says, ‘If the Twitter vote were representative, Ron Paul would be the Republican nominee.’”


The final presidential debate airs at 9 p.m. Monday.

CORRECTION: An earlier version misidentified Bluefin Labs as Blue Fin Labs.