Table 2 Information that is used to classify undocumented status, by total number of studies, and corresponding data source, data type, and measure type

Self-reported legal status, with no explicit query about undocumented status

Participants reported whether or not they had another legal status, through survey questions, but were not explicitly asked whether or not they were undocumented

Self-reported undocumented status

Participants reported explicitly whether or not they were undocumented either through survey questions or unprompted disclosure

Possession of a Social Security number

Classified as undocumented if participants did not possess a Social Security number

Type of health insurance

Classified as undocumented if participants possessed Emergency Medicaid or lacked insurance (e.g., “self-pay”)

Possession of institutional resources

Classified as undocumented if participant lacked institutional resources, such as a driver’s license or bank account

Statistical modeling

Classified as undocumented from statistical prediction models of demographic and economic characteristics

Concern about deportation

Classified as undocumented if participants expressed concern about deportation, such as “I have thought that if I went to a social or government agency I would be deported”

Personal or population characteristic

Classified as undocumented if participants belonged to a specific group, such as a day laborer, a parent in high-immigrant enrollment schools, or a person attempting to enter at port of entry

Unknown

Total