Since the late 1990s, the Ministry of Security and Justice has been attempting to monitor the size of the illegal immigrant population. It asked Methodology & Statistics researchers to provide these estimates.
Estimates of this kind can be made with the help of what is known as the ‘capture-recapture method’: estimating the total population based on the number of illegal immigrants who are arrested or detained. This led to a number of reports, which have been published on the website of the Ministry of Justice. The most recent report dates from the start of 2015.
We use a similar method when estimating numbers for the following groups:
- perpetrators and victims of domestic violence
- homeless people