That might seem eerily familiar because it’s the same punchline from one of the most infamous cases of scientific fraud in the last few years. In December 2014, political scientist Michael LaCour published a paper in which he supposedly evaluated the Los Angeles LGBT Center’s canvassers and found that they strongly and persistently reduced prejudices against same-sex marriage. Five months later, it turned out that his data was fabricated. His paper, exposed as a sham, was swiftly retracted.

The scandal was a huge blow to the LGBT Center—but the new study, published in the same journal, offers redemption. Their methods do work. And in an extra twist, the vindicating results come from the same researchers who uncovered LaCour’s fraud: David Broockman from Stanford University, and Joshua Kalla from the University of California, Berkeley.

They evaluated the same deep canvassing technique, and found even stronger results. For example, Lacour claimed that the conversations only work if the canvassers are themselves gay; Broockman and Kalla (after, y’know, actually doing some science) found that both transgender and non-transgender canvassers could change minds.

“This is something that other practitioners now know with confidence that they can adopt because they know it works,” says Broockman.

* * *

In November 2008, Californians voted to pass Proposition 8, an amendment that would stop same-sex couples from marrying. It was a huge blow for the LGBT community, not least because all the preceding polling suggested that the proposition would be defeated. “People had really expected to win,” says Dave Fleischer, now director of the Leadership Lab at the L.A. LGBT Center. “In the wake of it, people really wanted to do something, but they didn’t know what.”

He decided, simply, to talk to the people who had voted for the proposition. “I felt really smart because it was a great idea,” he tells me. “And I felt like an idiot because I’m 61 and I’ve been on the losing side of many elections, but it had never occurred to me to do this before.”

Over the next year and 13,000 conversations, Fleischer’s team of volunteers tried many strategies for swinging conservative voters to their side. Almost all of them failed. “One very popular idea was to tell our own stories; we thought that by itself would be enough,” he recalls. It wasn’t. “But when we tell a story and make ourselves vulnerable, it makes it easier for the voter to decide that we’re not going to judge them. And it makes it easier for us to elicit their story. That turns out to be by far the most important thing we do. Almost everything we do now is in service of getting the voter to honestly relive their experiences, recall it aloud, and reflect on it.”

Fleischer was on to something; he knew it. His own internal assessments told him that they were changing opinion, but he didn’t know to what degree, or how long the changes would last. He wanted an independent scientist to evaluate their approach. Enter LaCour. He randomly assigned voters to be canvassed on either gay marriage or recycling, and he was to survey them before and after. But while the canvassers did their thing, LaCour did nothing. And he might have got away with it too, if it weren’t for Broockman and Kalla.