Finally, the OECD records immigrants from only the top 5 or 10 countries from which they come to each OECD country. Thus, for example, the OECD figures for Canada would include specific information on the numbers of immigrants from China and Mexico, but not those from Jamaica and El Salvador. This is a problem when emigration flows are significant for the source country but small for the receiving country. Thus, particularly for small countries, our estimates of immigration to OECD countries other than the United States may be seriously understated. If, as a rule of thumb, we consider estimates to be unreliable when migrants to the United States account for less than one-third of the total of immigrants to all OECD member countries, then all estimates for immigration from the Asian and Pacific countries are reliable with the exceptions of those for Malaysia and Sri Lanka.
Turkey is also an exception.
The migration rate of highly educated individuals from China is about 3 percent. For Africa, the estimates are unreliable for Algeria, Senegal, and Tunisia, from which migrants go mainly to France. For most other countries in the sample, however, migration to OECD countries other than the United States is quite small, so the results derived for the United States remain essentially valid. For countries in the Western Hemisphere, the bulk of migration is to the United States, and inclusion of flows to the rest of the OECD makes little difference. The only exception is Jamaica, which has a considerable stock of migrants living in the United Kingdom.