The Barrier to Naturalization Index focuses specifically on the naturalization process and jus soli. It takes twelve requirements of the naturalization process into account: (1) good conduct, (2) willingness to integrate, (3) language skills, (4) dual nationality, (5) application complexity, (6) application fees, (7) state discretion in granting citizenship, (8) residency requirements, (9) jus sanguinis laws preventing jus soli naturalization of children, (10) jus sanguinis concerning children of parents born in country (double jus soli), (11) women allowed to maintain citizenship after marrying a foreigner, and (12) mothers when married to a foreigner being able to transfer citizenship to their children. It purposely excludes entry requirements, unemployment, and other variables.
Data were taken from the naturalization laws of each country and reports
from foreign country consulates in the United States.
For the index, components were grouped into four categories with a weighing scheme. The total index was constructed as a percentage of the maximum score of the highest-scoring country, so it varied from 0 to 1.