It looks like the results were from a simulation based on real-world data. This is certainly an interesting paper that I will have to spend more time on, but my initial critique is that out-migration was not stratified. I think the aggregate data would be different compared to that from stratifying by race or income. Additionally, know that the sources from the data broker include USPS changes of addresses, differences in magazine subscriptions, and whatnot but I don’t think data on couch-surfing-but-truly-homeless-individuals, new immigrants such as those from Afghanistan, individuals that are undocumented, and data on individuals that do not update their address with USPS when they move is adequately captured. This data is, likely, difficult to collect but I feel it could be a valuable contribution to this data(set).

I am also concered about the low power of the study. While the authors confirmed that the sample was actually representative, I wonder about the external validity.