pmsa

I've hit on this in the comments to other posts, but one of the nice features of weighted density is that it permits us to compare apples to apples (even though the comparison may be royal gala to red delicious).  Standard density is extremely sensitive to geographic boundaries.  This is why most debates over density quickly turn into squabbles over the proper geographic unit.  CMSA?  MSA?  Urbanized area?  Central city?  And then it's just a matter of time before someone brings up City  X's moutains or parks