igration rates of the highly educated in Eastern Europe and in middle income countries can be very high while the rate of immigration and emigration of the less educated is comparable. Mexico is the main exception with signi...cant emigration of less educated (7.8%) and minimal immigration. Finally the non-OECD immigration-receiving countries have comparable immigration and emigration rates, except for Singapore that has a very large in‡ow of highly educated workers.<sup>10</sup> The picture emerging from a ...rst glance at the data is that both the recent in‡ow of immigrants and out‡ow of emigrants has a high-skill concentration greater than those of native non-migrants for Western European countries as well as for the other rich countries included as comparison. This con...rms the data-based observation of Grogger and Hanson (forthcoming) and of Docquier and Marfouk (2005) but is in sharp contrast with the anecdotal image of unskilled immigrants ‡ooding Western European labor markets. This con‡icting perception is mainly due to the fact that less educated migrants formed a smaller share of the migrant ‡ow than the corresponding group for the native labor force, but they still outnumber the highly skilled migrants in absolute numbers. Hence the large number of less educated immigrants stand out and attract the public attention in most European countries. Germany is a good example to illustrate this point. Looking at the composition of the migrant ‡ow in the 1990s, the highly educated immigrants were 3.1% and the less educated immigrants 2.2% of their respective groups in the domestic labor market. However as 78% of the domestic labor force was less educated (and only 22% highly educated in 1990) there were still twice as many less educated immigrants relative to highly educated ones.

Another important observation is that the recent ‡ows are usually more educated when compared with the stock of immigrants already present as of 1990 (see table A4). Hence, if the impression on immigrants is based on the stock, rather than recent ‡ows, there may be a perception bias towards less educated migrants who possibly migrated long ago. Third, in spite of the fact that census data are better than o¢ cial immigration data, they may miss some undocumented migrants, especially in Western Europe. If those undocumented migrants that are missing from the census data are mainly less educated, the actual numbers of the less educated are understated by our data. We address this issue in section 5.1 by using estimates on the extent of undocumented migration in di¤erent destination countries.

Finally the perception of the skills of immigrants may be based on the occupations and the labor market performance of immigrants (rather than their formal education) as analyzed by Mattoo et.al. (2008) in the US labor market. In many cases, college educated immigrants are less productive and take less skilled occupations than college educated natives since their education quality, mostly obtained at home, might be less easily transferable or lower than those of the natives in the destination. The lower quality/downgrading of education levels for immigrants matter for our exercise as well. We address quality adjustment in the extensions of our simulation exercise in section 5.2.

In terms of the overall picture of migration across countries in the world, the nonEuropean Anglo-Saxon countries (US, Canada, Australia) attract highly educated immigrants, from all over the world and their native-born citizens tend not to emigrate. Western European countries seem to attract highly educated immigrants (from other European and

> 10 See our discussion below on undocumented migration, which tends to be less skill intensive, and how we try to account for this in our analysis.

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