Twitter, as it turns out, is not a good model of the world.

Hard as that is for the Twitter-addicted to believe, it is true, and a recent Pew Research study presents new evidence about the way that the platform leans.

In the United States, Twitter users are statistically younger, wealthier, and more politically liberal than the general population. They are also substantially better educated, according to Pew: 42 percent of sampled users had a college degree, versus 31 percent for U.S. adults broadly. Forty-one percent reported an income of more than $75,000, too, another large difference from the country as a whole. They were far more likely (60 percent) to be Democrats or lean Democratic than to be Republicans or lean Republican (35 percent).

Read: Everybody’s in a bubble, and that’s a problem

But Pew’s methodology was able to capture another layer of distortion: The Twitter of the platform’s fanatics is very different from the norm. In other words, Media Twitter is not Median Twitter.

First, Pew split up the Twitter users it surveyed into two groups: the top 10 percent most active users and the bottom 90 percent. Among that less-active group, the median user had tweeted twice total and had 19 followers. Most had never tweeted about politics, not even about Twitter CEO Jack Dorsey’s meeting with Donald Trump.