Is it useful? If so, how should we use it?

http://svi.cdc.gov

Interesting....and I would use it with caution. In my community, the colors change from highest to lowest within a few miles. Presumably, those responding to a disaster, like an earthquake, will have a notion of where best to direct their efforts. Presumably,in my neck of the woods, we will be somewhat more self sufficient and doing a little better on our own. But that is theoretical, at best. I am not sure I buy into all the factors that determine the rankings, although the general result is that higher income areas will respond better than lower income areas, which is probably more or less true.