In his session, “The Number of Undocumented Immigrants in the United States,” Mohammad Fazel-Zarandi, of the MIT Sloan School of Management, discussed groundbreaking research that he and Ed Kaplan and Jonathan Feinstein, both of the Yale School of Management, that indicates the actual number of undocumented immigrants in the U.S. is twice what previous estimates had indicated.
Their findings are based on a new approach grounded on operational data, and demographics and mathematical modeling that tracks and estimates annual population inflows and outflows in the United States from 1990-2016.
Previous estimates calculated the number of undocumented immigrants in the U.S. at 11.3 million, by subtracting the estimated lawful immigrant population from total foreign born population in the U.S., which is determined by census.
However, survey methods are not effective for identifying hidden populations (in this case, the undocumented immigrants living in the U.S.).
The goal of their method was to develop a conservative estimate using a controlled bias. Despite running 1,000,000 simulations, they were unable to duplicate the previous number of 11.3 million. Their findings estimate the actual number of undocumented immigrants in the U.S. is between 16.7 million (conservatively) and 22.1 million.
The model took into account multiple inflows (border crossers and visa overstays) as well as a number of overflows (voluntary emigration, deportation, adjustment status to documented, and mortality). They could not provide an unbiased result as there are too many unknowns, so chose to control the bias by underestimating inflows and overestimating outflows.
Since border crossers are hardest to estimate, as they are unseen, they used police apprehension numbers of immigrants attempting to cross the Mexico-U.S. border. In particular, they documented the number of times the same person was arrested crossing the border to create a model to estimate the number of people entering the country via border crossings. They also took into account visa overstays.
The new data provided by their research has multiple policy applications, to include helping social services better allocate resources, and provide more accurate information to decision makers.