Donald Trump has more than 55 million followers on Twitter. Elizabeth Warren, a senator from Massachusetts and a potential rival to Trump in the 2020 presidential election, has a little more than 4.5 million. But which of them is more successfully spreading their message beyond their follower base?

A new tool from Northeastern’s Center for Complex Network Research can identify Twitter users who are honing their ideas into tweets others want to share. The app boils an account down to a single number, called the Q-factor, to separate out users who are truly influential from those who are merely popular.

“If you have a high Q-factor, you’re going to get many more followers in the long run,” said Albert-László Barabási, who is a network scientist and director of the Center.

Users with a high Q-factor are those whose messages are being retweeted. They are engaging their followers, but also prompting followers to share those messages with their own networks. A tweet that is shared has a much greater reach than one with a lot of ‘likes.’

“When we retweet, we really mean it,” said Barabási, who is a Robert Gray Dodge Professor of Network Science and Distinguished University Professor. “It’s a much stronger endorsement.”

Trump may have a larger follower base, but his Q-factor is only 29. Warren has a Q-factor of 41. Her tweets are much more likely to reach a wider network. The Q-factors of both Warren and Trump are trumped by that of another well known figure who will not be running for president but whose influence over national political discourse is evident: Barack Obama, whose Q-factor is a cool 64.

A high Q-factor doesn’t guarantee a politician will win in the polls next week, Barabási said. Warren’s Republican opponent, Geoff Diehl, has a Q-factor of 246. But he currently has only a 0.2% chance of winning, according to FiveThirtyEight. Politicians with small but passionate group of followers will wind up with a high Q-factor, but may just be shouting into a very reflective echo chamber.

To determine an account’s Q-factor, the app takes the number of retweets it has and scales it by the number of people following that user. This means a person’s Q-factor doesn’t depend on the number of followers.

“That’s where the interesting science is,” Barabási said, because it’s not a direct relationship. His calculations have to account for the fact that engagement inevitably drops off as a following grows larger. The details of this scaling formula are the subject of an upcoming research paper.

Barabási designed the app based on his previous work studying how to determine whether a scientist will have a successful career.

“Instead of retweets, it was how many citations you get,” said Barabási, whose upcoming book The Formula: The Universal Laws of Success includes a chapter on the research. “The question was how good are you at turning your ideas into impactful discoveries.”

With the help of Onur Varol, a postdoctoral researcher who helped build a bot-detector for Twitter, Barabási has expanded this idea from science to social media. How good are you at turning your ideas into messages that your audience will want to share?

Once you’ve logged into the app, you can pull the Q-factor for any Twitter account. You can see that with a Q-factor of 118, Captain America (Chris Evans) is narrowly edging out Wonderwoman (Gal Gadot) at 106. Both of them are blowing away Ironman (Robert Downey Jr.) and Deadpool (Ryan Reynolds), who have Q-factors of 65 and 63, respectively.

So how do you improve your own Q-factor?

“Start monitoring it,” Barabási said. The app allows you to see which of your messages were retweeted the most. “It’s all about how effectively you communicate.”

Take a look at some of the matchups below to see who is doing a better job of reaching a wider community: