A June 2012 Gallup survey found that just 12 percent of Americans had volunteered for a political campaign, donated to a campaign or attended a political rally. The venerable General Social Survey reported in 2014 that just 28 percent of Americans said they’d ever gone to a political meeting or rally. In contrast, nearly 60 percent of all Americans eligible to vote turned out in 2012.

The fact that only a tiny slice of the nation attends campaign events wouldn’t matter if that slice were a good representation of the entire voting public. Polls, after all, may survey 1,000 people or fewer. But while pollsters take care to make sure their results are representative of the electorate at large, the kind of people who show up at candidates’ rallies come from the unusually enthusiastic and committed end of the spectrum.

“People who go to rallies are more involved in politics and more motivated by a particular candidate’s message,” HuffPost’s Natalie Jackson wrote earlier this month. “They are probably more likely to vote than those staying at home on the couch, but many of those on the couch actually will get up to vote. Voting is generally a much less burdensome method of participating in politics than attending a campaign rally.”