There is an asymmetry in international migration. The right to leave the country in which one resides is now established, although it is not universally guaranteed. On the other hand, the right to enter a country is still limited by the recognition of the sovereignty of national states and their right to control the entry of foreigners into their territory. There are therefore no records of exits (emigration) but only of entries (immigration). These methodological constraints on statistics of emigration are similar for all European countries. For this reason, the best way to study a country's emigration is to compile data on the entry and stay of its emigrants in the destination countries, thus creating the so-called "mirror statistics": the emigrants of a country are studied as immigrants in the destinations. This is the approach taken by international organisations such as the United Nations, the World Bank and the OECD. It is also the approach taken by the Portuguese Emigration Observatory, which compiles, makes available and analyses statistics on Portuguese immigrants in the countries where they emigrate. As a rule, but not always, this option has advantages over alternative procedures, such as those used by the Portuguese National Statistics Institute and Eurostat, but it involves methodological problems that need to be assessed. This communication discusses the problems with this method and how they affect the quality of the data in mirror statistics to varying degrees. It also identifies some procedures to limit the problems, recommendations to take into account when analysing mirror statistics and the complementary use of alternative statistics. [Panel: Survey data in migration research, org. by Agata Górny, University of Warsaw]

Rui Pena Pires, Emigration Observatory

Emigration,Immigration

• Sociology - Social Sciences