Summary of report for a research project for UDI

Developing methods for determining the number of unauthorized foreigners in Norway


The expected total number of unauthorized residents with non-EU origins is estimated to be 18200 by 1.1.2006. This constitutes 0.4 percent of the official residents population in Norway. The estimate has, however, a large degree of uncertainty. Lower and upper bounds (95 percent confidence interval) are 10500 and 31900 respectively. Of the estimated total for all unauthorized residents, 12300 are estimated to be previous asylum seekers. The rest, 5900, are persons that have never applied for asylum.

These results appear in an analysis Statistics Norway has done for the Norwegian Directorate of Immigration (UDI). The analysis consisted of developing statistical methods, making use of existing data sources, for estimating the number of unauthorized foreign citizens at a given time in Norway, together with the degree of reliability related to these estimates, as expressed by confidence intervals.

The method of estimation is based on a statistical model describing statistical relationships in the available data which, however, was not collected for the purpose of this project. The data sources used are the Central Population Register (data about persons registered living in Norway), registrations in UDI (unauthorized persons facing expulsion), and from the Police (data about foreign citizens facing criminal charges). Information about country of origin and possible refusals of asylum applications are utilized.

The data are prepared in aggregated table form such that no person can be identified. Statistical associations assumed in the model do not express any cause-effect relationships.

The report is prepared by Senior Researcher Li-Chun Zhang. It is accessible at