In his statement calling for a complete ban on Muslim immigration to the United States, GOP presidential frontrunner Donald Trump cites as a key part of his argument a discredited opt-in online survey by a far-right anti-Muslim conspiracy theorist.

The poll, from a think tank called the Center for Security Policy (CSP), reported that a quarter of the American Muslim population believe that violence against Americans is justified.

CSP is led by Frank Gaffney, a far-right activist who theorized that the Muslim Brotherhood has infiltrated the U.S. government as well as the work of tax lobbyist Grover Norquist. His think tank also propagates the myth of Muslim “no-go zones” in the European Union. And Gaffney claims that the U.S. Missile Defense agency logo was altered by the Obama administration to “reflect a morphing of the Islamic crescent and star with the Obama campaign logo.”

The poll itself was conducted in a manner that was unscientific. Shortly after it was released in the summer of 2015, the Bridge Initiative at Georgetown University contacted the niche conservative pollster who conducted it, Polling Company/Woman Trend, and found out that the poll was conducted as a “non-probability based, opt-in online survey” — meaning that it has no statistical validity.

Trump also vaguely cited “Pew Research, among others.” This 2013 Pew poll asked Muslims in various countries a different question: if they thought suicide bombing in the defense of Islam was at least sometimes justified. The question was not about violence against Americans.

Among American Muslims, 81 percent said suicide bombing or other forms of violence against civilians in the name of Islam are never justified, while 1 percent said they could be often justified and 7 percent said they could be sometimes justified.

Globally, an overwhelming majority of those polled said suicide bombings were not justified. In 15 of the 20 countries surveyed, 15 percent or less said it was often or sometimes justified. The outliers were led by Afghanistan (39 percent) and the Palestinian territories (40 percent).

When it comes to the specific issue of ISIS, the vast majority of respondents in every Muslim-majority country polled by Pew were opposed to the organization. In Indonesia, the most populous Muslim-majority nation, ISIS yielded only 4 percent support, with 79 percent having an unfavorable view of the organization. In the Palestinian territories, 84 percent had an unfavorable view of the group; in Lebanon, a full 100 percent of Lebanese had an unfavorable opinion.

Correction: An earlier version of this story incorrectly described the group the CSP poll surveyed. It was Muslims in America, not worldwide.