In July 2007, the European Union adopted a number of principles aimed at harmonizing European statistics on migration flows. Unfortunately, it is likely to take quite some time to put theory into practice in this area, given the enormous differences between the statistical systems of the member states.
By way of comparisons between various European countries (France, Netherlands, Sweden, Denmark and Norway), Michèle Tribalat shows here how much the methods and definitions used to measure migration phenomena differ, and hence how difficult it is to make such comparisons or, indeed, to evaluate the demographic effects of foreign immigration.
To begin with, she shows, for example, that "net migration change", as calculated in France, is not a reliable indicator and does not reflect actual developments. Hence the desirability of going further and examining the demographic effects of alien immigration, covering not only the direct contribution to the population of a country, but also the indirect (descendants). It is, without a doubt, the assessment of this contribution that is likely to make European statistical harmonization very complicated. The definitions employed in the various countries mean that some mix the generations, some take no account of the mobility of nationals (as a result of which their children born abroad become persons of foreign origin!), and some leave the colonial past out the reckoning etc. In short, if we are to measure migration phenomena in Europe effectively and on a comparable footing, it is imperative, above all, that we develop a precise definition of what we are aiming to measure (and this article sheds important light on this question), in order that the various countries may equip themselves with the proper means of measurement (France has a long way to go to do this).