A Yale University study showing the illegal immigrant population might be twice as large as generally accepted exploded on the internet this week but is drawing skepticism from both sides of the debate.
The study, published in the journal PLoS One, used mathematical modeling on demographic and immigration data to estimate that the United States has 16.7 million to 29 million illegal immigrants. The middle estimate comes to 22.1 million.
That figure far exceeds the consensus estimates, including the 10.8 million figure for 2016 put out in February by the Center for Migration Studies, which favors granting legal status to immigrants living in the United States without permission.
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Robert Warren, a former Census Bureau demographer and visiting fellow at the think tank, blasted the Yale study.
“It’s totally flawed and should never have been published … The 22 million number is just a number. There’s nothing around it,” he told LifeZette.
Warren said the Yale model suggests that 17.5 million immigrants came from Mexico in the 1990s.
“There’s a lot of evidence that that’s impossible … That would have meant that 12 million Mexicans would have been missing from Mexico, and they would have noticed,” he said.
Alex Nowrasteh, an immigration expert at the libertarian Cato Institute, said if the illegal immigrant population in America were even at the low end of the Yale study’s estimates, it would be evident in other statistics.
“Five million more illegal immigrants should show up in the birth rate,” he said. “There should be more kids in school than there are … That many people just can’t hide. It would be almost as unbelievable as somebody arguing that there are none.”
“That’s a really wide margin of error, it’s kind of all over the place.”
Chris Chmielenski, deputy director of the low-immigration advocacy group NumbersUSA, said he has no reason to challenge the estimates of the Department of Homeland Security and of researchers on both sides of the debate. Those estimates generally are about 11 million, far less than the Yale estimate.
“This seems to be more of an outlier and should be treated as such,” he said.
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Spencer Raley, a research associate at the Federation for American Immigration Reform, said it is reasonable to conclude that hard-to-count illegal immigrants exceed common estimates. But he added that 22 million seems like a stretch.
“It gives credence to the idea that we’re underestimated it,” said Raley, whose organization favors lower immigration levels. “I don’t know that I agree with their methodology.”
Raley noted that the high and low ends of the Yale study vary by 13 million people.
“If you’re looking at doubling the illegal immigration population every 10 years, you’ve got serious, serious problems.”
“That’s a really wide margin of error,” he said. “It’s kind of all over the place.”
Not everyone finds the Yale estimate implausible. Although the Washington-based Center for Immigration Studies agrees that the 11 million estimate likely is correct, a fellow at the think tank said the number could well be larger.
Don Barnett, who has been a fellow there since 2003, pointed to a 2005 article by two Bear Stearns financial advisers who pegged the estimate at 20 million, based on a rise in the amount of money wired to Mexico and housing permits in three New Jersey communities with growing immigrant populations.
“They also came up with twice that amount,” he said.
If the Yale study is accurate, however, what would that mean? The experts diverge.
“If you’re looking at doubling the illegal immigration population every 10 years, you’ve got serious, serious problems,” Chmielenski said.
Removing the illegal immigrant population would have a far bigger impact on wages and the labor market if the number were north of 20 million rather than 11 million, Chmielenski said.
“Imagine how many more opportunities there would be opened up for Americans who are competing with immigrants for jobs,” he said.
One consequence of a much larger illegal immigrant population is that illegal immigrant crime would be a much smaller problem than people assume, said Cato’s Nowrasteh. The logic is straightforward — the same number of crimes by illegal immigrants divided by a much larger illegal immigrant population results in a much lower crime rate.
“I just like simple rates like that,” he said.
But Nowrasteh said there is reason to be suspicious of the Yale study. It would mean that illegal immigrants would be committing crimes at lower rates than legal immigrants — even though illegal immigrants tend to be younger, poorer and skewed toward men, three groups more prone to crime.
But Raley challenged the reliability of data on illegal immigrant crime.
“He’s assuming that we know how many crimes illegal aliens are committing every year,” he said.