22.1 million people are in the US illegally

MIT's Sloan School of Management announces,

There are roughly twice as many undocumented immigrants in the U.S. as commonly believed, according to a sweeping new study by MIT Sloan School of Management's Mohammad Fazel-Zarandi, a Senior Lecturer in the Operations Research and Statistics group, and his colleagues, Edward Kaplan and Jonathan Feinstein, both from Yale School of Management.

The study, which is published today in PLOS ONE, estimates that there are about 22.1 million undocumented immigrants in the U.S.; the most prominent current estimate is 11.3 million. Even using parameters intentionally aimed at producing a conservative estimate, the study finds a population of 16.7 million undocumented immigrants.

"Immigration policy is a hot-button issue in the U.S. and the question of how to address undocumented immigrants—that is, the people living here without permission from the American government—provokes passion on both sides," says Fazel-Zarandi. "The fact is, though, if you want to solve a problem, you need to know the scope of it. Debates about the amount of resources to devote to this population and the relative benefits and disadvantages of alternative policies—including deportation, amnesty, and border control—depend greatly on having a correct estimate. The number sets the scale."

Read more here.