I started reading this article, then found myself skimming more and more as it became flakier and flakier. Now, because I just skimmed most of it, I may be mis

I started reading this article, then found myself skimming more and more as it became flakier and flakier. Now, because I just skimmed most of it, I may be missing some important points -- but my impression is that the authors are so bound up in the details & statistical tests that they can't see any big picture. For example, in discussing household moves they talk about which zipcodes people choose to live in, as if they had perfect freedom of choice. But I don't see where they account for median income. How are we to know if people in a "harbinger" zipcode can even afford to move to a "Group 1" zipcode? Or if it would be a convenient distance from their employment? I simply can't see putting much or any faith in these "results".