Nisbett describes his research well, and it seems to have been done in a rigorous way. He is careful to explain that "Asians" and "westerners" are of course very broad categories, and large variations exist within them. Nonetheless, clear qualitative differences can be found between them, and hence they are generally acceptable categories. Two minor objections can be made. First, almost all of his subject were university students, which, although a popular group for sociology and psychology research, may not be representative of the population as a whole. And second, although a few studies included asians americans (usually second-generation people of asian descent living in the united states), no studies included "american asians" (americans who now made their home in asia). Perhaps the latter group is too small to locate for research studies. These two points are unlikely to drastically affect the research results.