My point is, the diaspora is spread enough that you can rule out climate and air quality by comparing cohorts within the same climate and same air quality. Most cities in Europe don’t have terrible air quality for example. Your suggestion that big Asian cities have more relevance in the result goes against how you actually do statistics.
Statistically significant portion might be in just a handful of similar cities. There are big cities in sa.
My point is, the diaspora is spread enough that you can rule out climate and air quality by comparing cohorts within the same climate and same air quality. Most cities in Europe don’t have terrible air quality for example. Your suggestion that big Asian cities have more relevance in the result goes against how you actually do statistics.