What happens to every rubric of U. S. economic, national security, and social policy when a key demographic is revealed to be not only wildly wrong but is doubled?  We’re about to find out.

A new study released by Yale University and MIT reveals that the previously accepted number of illegal aliens in the U.S. represents only half the actual number.

The report finds that there are 22 million illegal aliens, not 11 million as previously believed, living in the United States.

The Hill reports:

The undocumented population in the United States could be twice as large as the most commonly-used estimate, according to a research study published Friday in the scientific journal Plos One.

The paper, led by Mohammad M. Fazel-Zarandi, a researcher at Yale and Massachusetts Institute of Technology, estimates there are 22.1 million undocumented immigrants in the United States.

Fazel-Zarandi’s study compared inflows and outflows of immigrants as well as demographic data. According to the report, the number of undocumented immigrants could be as low as 16.5 million, or as high as 29.1 million.

“We combined these data using a demographic model that follows a very simple logic,” Edward Kaplan, a co-author of the report, told Yale Insights. “The population today is equal to the initial population plus everyone who came in minus everyone who went out. It’s that simple.”

Most previous estimates, based on the U.S. Census Bureau’s annual American Community Survey (ACS), place the undocumented population at around 11 million people.


[Image source: PLOS online]

The study itself notes that even if the researchers use “unrealistically” “conservative assumptions,” the minimum number of illegal aliens residing in the U. S. would be 14-16.5 million, not the 11.3 million typically cited.

The results of our analysis are clear: The number of undocumented immigrants in the United States is estimated to be substantially larger than has been appreciated at least in widely accepted previous estimates. Even an estimate based on what we view as conservative assumptions, in some cases unrealistically so, generates an estimate of 16.7 million, well above the conventional estimate of 11.3 million.

The mean of our simulations, which range over more standard but still conservative parameter values, is 22.1 million, essentially twice the current widely accepted estimate; the ninety-five percent probability interval is [16.2,29.5].

Even for the scenario presuming net inflows of 0.5 million per year for 1990-98 our results still exceed the current estimates substantially. The mean estimate is 17.0 million with a 95% probability interval of 13.5 million to 21.1 million. The conservative estimate for this scenario is 14.0 million, still significantly above the widely accepted estimate of 11.3 million.

It would seem that no matter how they crunch the numbers in their simulation, they can’t arrive at the 11.3 million.

Their final estimate is 22.1 million, though they do conclude their report by noting it could be as high as 29.5 million.

Our results lead us to the conclusion that the widely accepted estimate of 11.3 million undocumented immigrants in the United States is too small. Our model estimates indicate that the true number is likely to be larger, with an estimated ninety-five percent probability interval ranging from 16.2 to 29.5 million undocumented immigrants.

Watch the researchers discuss their methodology and findings:


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