MARRIAGE between people of different backgrounds is one of the best barometers of social integration, especially for migrants. Few things say that someone born abroad is becoming part of his or her adopted country than marrying a local. Unfortunately, getting good figures on “mixed marriages” is hard. Marriage licences and censuses contain all sorts of information, but not all of it useful. All the more reason, then, to welcome a new study on mixed marriages in Europe by Giampaolo Lanzieri.

Mr Lanzieri, who works at Eurostat, the European Commission’s statistical body, is one of the most careful students of social trends around. He defines “mixed marriage” as one between a native-born person living in a country and someone born abroad. This definition is clear and means his figures are consistent and comparable from country to country. The drawback is that it makes them imperfect guides to integration. If a man born in France of Algerian parents marries a girl from his parent’s home town, that counts as a “mixed marriage” (he was born in France, she in Algeria). But it is the opposite of integration through marriage. If, on the other hand, a British man of Caribbean extraction marries a white British girl, that does not count as a mixed marriage, even though it is clearly an example of ethnical and racial integration.

Still, despite these qualifications, these are the best national figures going and the only ones that cast a clear and consistent light on marriages with foreigners in Europe. They show three trends.