Counting immigrants: the combined use of administrative and census data in Italy

Maura Simone, Istituto Nazionale di Statistica (ISTAT)
Mauro Albani, Istituto Nazionale di Statistica (ISTAT)
Angela Silvestrini, Istituto Nazionale di Statistica (ISTAT)

In 2011 the XV General Population and Housing Census enumerated 4,027,627 foreigners resident in Italy. The 2011 Census was based largely on the use of registers. The choice of starting from administrative sources was addressed both to exploit the information contained in the registers and to pursuit the greatest coherence between administrative and census data. Official administrative surveys represent precious sources for monitoring the largest part of the phenomenon of immigration in Italy. It is well known that administrative data suffer of oversize counting as it is very difficult to register emigration of foreigners, leaving the Country without communicating their departure to the municipality. In Italy the administrative laws ordering the population registers place restrictions to the cancellation of these foreigners from the archives. On the other hand, particularly in the case of foreigners Census data suffer of undersize counting for different reasons: high internal mobility, precarious housing conditions, cultural problems, long term absence from home due to work, etc. Census results, combined with the revision of population registers show that the attainments to Census response is different according to the nationality but also to other demographic characters. For the first time at the individual level, after the XV Census it has become possible to understand the different weight of these variables through the SIREA (SIstema di REvisione delle Anagrafi). The aim of this study is to describe the changes in foreign population stock and in migration dynamics at the municipal level, through the analysis of the data coming from the different Istat surveys; the study tries also to verify which are the more representative sources to better evaluate the foreign population presence on the Italian territory.