For years, despite much evidence to the contrary, establishment pundits and politicians have insisted that Bernie Sanders is unelectable. Last week, they got a gift: political scientists David Broockman and Joshua Kalla, writing in Vox, reported that their new study suggests Sanders’s electability could be a “mirage.”

The pair’s basic argument is that while Sanders might seem to have the best chance against Donald Trump, the polls in Sanders’s favor often fail to weight responses by the “likely electorate” — and, consequently, they underplay how much his electoral strength relies on getting younger voters to the polls. Sanders, the authors claim, would need an 11 percent turnout bump among voters thirty-five and under to do “as well” as the “more moderate candidates.” If they’re right, that would be a historic increase. It sounds daunting for Sanders supporters.

But how exactly did Broockman and Kalla reach this conclusion? Recognizing that stated intention to vote can be unreliable and that young people tend to turn out at very low rates, the scholars replaced participants’ stated intention with the actual turnout of those demographics in 2016. In addition, the authors took eligible voters who said they would go third party, were undecided, or would not vote and, if they were “leaning toward” one of the candidates, treated them as Democratic Party voters. After making these assumptions, Broockman and Kalla arrived at their result: “Sanders runs 0.6 to 3.9pp behind the moderates in terms of performance against Trump.”