Operational Data Beats Surveys on Undocumented

Instead of relying on household surveys that can undercount hidden populations, use operational inflow/outflow data—border apprehensions, visa overstays, deportations, mortality and emigration—to model the stock of undocumented residents. Applying this method yields a much higher estimate (about 22 million vs. ~11 million) for 1990–2016, even under conservative assumptions. — If survey methods systematically undercount the undocumented, immigration policy and resource planning are being made on a mismeasured baseline.