"black immigrants from Africa average the highest educational attainment of any population group"
-- this is because of selection bias: only the brightest Africans get the chance to immigrate to the US.
-- this is because of selection bias: only the brightest Africans get the chance to immigrate to the US.
First, there's already an established Asian community that has been here for a long town. There are old Chinatowns, Little Tokyos, etc. There's no Little Nairobi that I've ever heard of. So many Asians aren't actually recent immigrants.
Second, regarding those who are, many Asians aren't here by merit alone. Sure, there are some (like my parents) who came from a poorer background and managed to make it to the US. But increasingly they are supplemented by people who were born into rich families (fu er dai, "second generation rich people"). Now, I don't have statistics to back this up, but this seems to be more prevalent now because of China's recent economic boom. It's just my own theory, anyway.
Also, if you were to visit some Chinese social event (church for example), there are distinct groups of people. It's not just middle class white collar workers, there are also lower class people and older people. There are multiple generations, from the older people (mostly Cantonese speaking, at least where I live), to the middle aged people, to the young people (either ABCs or international students).