How many immigrants live in Spain? an alternative estimation to the population register based on the 2007 national immigration survey

Luis Rosero-Bixby, Universidad de Costa Rica
David Reher, Universidad Complutense de Madrid
Teresa Castro Martin, Spanish National Research Council (CSIC)
Marta Roig, United Nations
María Sánchez Domínguez, Universidad Complutense de Madrid

The main tool for estimating the number of immigrants in Spain is the municipal population register (padrón continuo) which, since 1996, has become a continuously updated source of population data. In recent years this source has been suspect because of what has been thought to be a structural tendency to overestimate the number of current immigrants in the country. This is so because double-registration is difficult to detect among foreign residents without a unique identity document, and because immigrants do not usually deregister when they return to their country of origin or move on to another country in the EU. The very recent National Immigrant Survey (Encuesta Nacional de Inmigrantes - ENI), carried out by the Spanish National Institute of Statistics in February 2007 provides a unique opportunity to generate alternative estimates of the number of immigrants. In this study, current fertility estimates of main immigrant groups derived from the ENI will be used in combination with data on births by parents’ nationality contained in the national birth registry, which has a full coverage of births, in order to obtain alternate estimates. The estimation process has two steps: (a) estimation of the number of foreign women of reproductive age, based on the number of births to foreign mothers; (b) estimation of the size of the foreign population based on the number of women of reproductive age. These new estimates will then be compared to those derived from the population register, in order to evaluate its quality and identify potential deficiencies.