Further thoughts: (1) I doubt the IRS has citizenship information in its files. (politics.stackexchange.com)
Applicants that we were unable to classify were categorized as having missing citizenship information, and we included a dummy variable in the model for those cases. (science.sciencemag.org)
Individual scholar citizenship information will not be retained by the Global Citizens Program team and will be limited to those with a need to know. (democracyprep.org)