My intuition is that the phenomenon of the subprime loan is related to the rapid rise in housing prices that haven't been matched by comparable rises in money wages. The implication is that people are paying a lot more of their incomes in mortgage payments than once they did. That, in turn, would be more prevalent in parts of the country where there's been more speculative price increases than in areas that have experienced less of a bubble. More where you are than who you are.
He asks whether this intuition is correct. Having spent the late 80's and early 90's at Freddie Mac, my guess would be that it is not. My guess is that subprime borrowers are subprime borrowers, meaning people with flaws in their past record of managing credit.
One thing that happens in mortgage lending is that rising home prices cover up a multiple of sins. You can get away with really lax lending standards in a rising market, even to the point of tolerating a bit of fraud. What happens is that when people get into trouble with making payments but their houses have appreciated in value, they almost never go to foreclosure. Instead, they can sell their house, repay the loan, and walk away with some cash.
Looking at data from, say, 1998 through 2005, a lender would say that subprime lending was a high-margin, low-risk business. So standards got pretty loose. Now that house prices are not going up so much, some of the lenders are getting burned. When the borrower's bad spending habits get the better of him, he can no longer bail out by taking the profits on his house. He just stays and waits for the lender to come after him.
My guess is that the typical defaulter today is not some prudent individual who happened to buy a home that strains his paycheck. Instead, my guess is that the typical defaulter is somebody who is poor at managing spending and credit. Of course, either defaulter is going to appear to be "over his head."
UPDATE: Following up on my blog post (just kidding), the WSJ reports,
Fraud appears to be one reason for a recent rash of defaults occurring within the first few months of subprime loans. One hint that fraud might be a problem at New Century came in the company's disclosure last week that in December, borrowers failed to make even the first payment on 2.5% of New Century's loans. Normally people who borrow in good faith manage to make at least the first few payments.
Lenders loosened standards considerably in the first half of this decade. Home prices were climbing so fast that borrowers who couldn't keep up on payments could almost always sell their homes for a profit or refinance into a loan with easier terms. That emboldened lenders to offer loans with little or no down payment. Sometimes they let borrowers skip burdensome paperwork such as digging out tax forms to prove how much money they made.