Also Sam why is there such divergence in housing markets across the country if you think it is so interrelated with income?
Because we're still dealing with contraction of the various housing bubbles in the various markets within the various asset classes. Obviously, there are some housing markets where there was never much of a bubble to start off with, so there won't be much change there, but the variation was great.
As a rule, lesser properties with lesser owners (in terms of income, credit, loan type) tend to default first and then we go up the income line. As Torie said, the rich are holding on, but not buying. Certain areas tend to go first (California, Nevada, Florida - where the loosest lending was and second home exposure) and certain areas tend to go last (we've finally started to see the break in Manhattan housing over the last quarter, the area close to DC is being held up by government, for now, whereas the areas further away have already gotten killed, but that deals with factor #1 moreso).
Anyway, so the 2.0/3.0 figures are broad-based, but with a specific housing market you have to analyze that market first (and the neighborhood). Or so is my point.
Reasons
1) Property taxes
2) Lending practices - More important than you might think. Texas has some of the strictest lending practices in the nation, if not the most. It's always been that way, but the reqs got much more strict after the S&L crisis during the 1980s, which hit Texas harder than anywhere else. None of that $40,000 income $400,000 loan crap there. If you had $40,000 income, you'd be lucky to get $100,000 loan unless maybe you had stellar credit. HELOCs weren't legal until 2000 and even then you can only get 80/20 loans.
3) Availability of open land for building.
There are some others that I've missed, but these are the big ones.