Centre sampling technique in foreign migration surveys: A methodological note

We address in this article the problem of performing a statistical survey of a group of individuals present in a certain population when information about the complete list of the members is missing or partially unknown. This problem is particularly relevant in immigration analysis, where many of the individuals are possibly illegal migrants and therefore not formally registered or accounted for in official statistics. We propose a sample method that integrates information provided by specific surveys and subjective knowledge available to the researcher about the geo-social reality of interest.