Numbers

Methodology for mapping migration

In order to map migration into and around the EU, and particularly to understand intra-EU mobility, you need to start by identifying three key things:

  1. Definitions: how do you define the different groups of people you talking about?
  2. Sources: what sources of information are available, and what definitions are they making use of?
  3. Dynamics: what do these sources tell us about the dynamics of these people’s movements — that is, not only when and where people move within Europe, but also whether they stay, return, or move on to somewhere else.

To identify and analyse a range of trends, the REMINDER team considered a variety of different definitions of a ‘migrant’. These included definitions based on a person’s citizenship (are they a citizen of an EU or non-EU country?), country of birth (were they born in the EU28 or outside the EU?), and their country of previous or next residence (depending on whether immigration or emigration is the focus).

The team investigated what sources of data were available, and what level of detail they provided. Much of the available data on migration within the EU is administrative data (for example, population registers, censuses, and administrative records of naturalisations, asylum claims and other legal processes). However, data is also available from national and international surveys of migrant groups. Administrative data tends to be more comprehensive, whereas survey data tends to be more detailed. To draw meaningful conclusions, the researchers needed to take into account the different ways in which migration was being defined and recorded across these sources: for example, defining migration by country of birth gives a consistently higher count of intra-EU migrants than defining it by country of citizenship.

The REMINDER team has produced a searchable ‘database of databases’ to assist those searching for data on migration within the EU, available below.

Once the definitions and data sources had been clarified, the team were able to bring together data on key issues in migration debates: migration and mobility flows around the EU; ‘stocks’ (populations) of migrants and mobile citizens in different places; survey data detailing factors like migrants’ labour market outcomes, information on study migration and irregular migration.

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