Real Estate Research
Real Estate Research provides analysis of topical research and current issues in the fields of housing and real estate economics. Authors for the blog include the Atlanta Fed's Kristopher Gerardi, Carl Hudson, and analysts, as well as the Boston Fed's Christopher Foote and Paul Willen.
March 31, 2010
Anti-foreclosure policy and aggregate house price indexes
A new paper by researchers at the New York Fed and New York University argues that the Federal Housing Authority (FHA), the government's insurer of relatively high-risk loans, is seriously understating the amount of risk in its portfolio. The paper makes a number of different points, but we want to comment on one claim in particular that has policy relevance beyond the issue of FHA risk. In fact, if this claim is correct, then any policy designed to reduce foreclosures by eliminating negative home equity could face significant problems when put into effect.
Repeat sales indexes a poor predictor of individual home price
The specific issue we want to address is how well an aggregate house price index can predict the price of an individual home. A number of aggregate indexes measure average house prices for a particular area, from the national level to the ZIP-code level. Often, these indexes are based on repeat sales, meaning that they combine the price changes of individual homes over time. If a house sold for $200,000 in 1997 and $220,000 in 2001, this repeat sale provides a data point indicating that house prices rose by 10 percent from 1997 to 2001. It is true that the 2001 buyer might have gotten a great deal in that the house really should have sold for more than $220,000 at the second sale. However, the assumption is that the influence of good and bad deals washes out when data from many repeat sales are aggregated together. If they do, then researchers can infer the average, overall path of house prices.
The problem occurs, the authors of the paper say, when one uses the resulting aggregate index to predict the price of an individual home. Consider someone who purchased a home for $200,000 in 2007. Now assume that over the next two years the aggregate house price index for that particular area declined by 10 percent. The authors point out that the decline in the index does not necessarily mean that this particular homeowner would have sold the house for $180,000 in 2009. The owner may have taken extremely poor care of the house, or a beautiful park that was across the street from the house at the time of purchase may have become a strip mall. In either case, the homeowner was likely to have sold for less than $180,000. On the other hand, the homeowner may have made some improvements to the home that would have resulted in a sale of more than $180,000.
Research paper provides careful analysis of valuation errors in aggregate indexes
Potential problems with repeat-sales indexes were well known before the FHA paper was written. What the new paper contributes is a careful analysis of how large these so-called valuation errors can be and how they might relate to the probability of having negative equity. Using residential sales from Los Angeles County, the authors compare the actual sales prices of houses with predictions generated by different aggregate price indexes. The authors make two important findings.
First, the repeat-sales indexes are often biased, in the sense that the mean of the predictions does not match the mean of the recorded prices. For 2008 and 2009, repeat-sales indexes tended to overpredict house prices by 7 to 18 percent. In 2007, the indexes underpredicted house prices by about 4 percent. Second, dispersion in individual valuation errors is large—the standard deviation of valuation errors is about 20 to 25 percent, depending on the aggregate index used. Putting these two facts together gives a clear message: Using standard methods, it is difficult to predict what any individual house will sell for at any particular time.
Valuation errors undermine mortgage balance reduction policies
On a general level, this observation is not an indictment of the FHA, since a lot of other people also use aggregate indexes to infer prices of individual homes—including us. Moreover, without knowing the ins and outs of the FHA's default-prediction model, it is hard to know the quantitative importance of valuation errors in the calculation of FHA risk. But moving beyond this issue, it is not hard to see how large valuation errors could undermine the effectiveness of a policy that attempted to ease foreclosures by reducing mortgage balances for individual negative-equity homeowners. As we have blogged recently, some observers have claimed that many, if not most, foreclosures occur because owners with large amounts of negative equity simply walk away from their homes. The ostensible policy implication is to reduce these homeowners' mortgage balances to give them more of an incentive to stay.
If valuation errors are large, however, it is very difficult to know who has severe negative equity and who doesn't. This problem undermines the effectiveness of balance-reduction policies. Effective policymakers must know how to price individual homes to assess the depth of negative equity for those homes. Consider two homes that, according to an aggregate price index, have 30 percent negative equity. That amount may or may not be severe enough to get an owner thinking about walking away. If it is, then an appropriate policy might reduce both homes' mortgage balances by 20 percent, thereby reducing the negative equity to about 10 percent. (Leaving a little bit of negative equity is probably a good idea in practice because it may prevent homeowners from selling the moment that a balance reduction is made.)
Effective foreclosure prevention would consider both job loss and negative equity
If in reality one of these homes actually has 50 percent negative equity and the other has 10 percent negative equity, then the balance-reduction policy is likely to prevent no foreclosures. The owner with 50 percent negative equity remains underwater, to the tune of 30 percent, so is probably still thinking about walking away—according to the theory of default that motivated the balance-reduction policy in the first place. On the other hand, the owner with 10 percent negative equity was not going to walk, unless perhaps a job loss went along with the negative equity. But if the combination of job loss and negative equity is the real problem in the housing market rather than severe amounts of negative equity alone then we can devise much more cost-effective policies to reduce foreclosures than large-scale balance reductions.
The authors of the paper do not discuss balance reductions. However, in other papers, they argue that anti-foreclosure policy should consider balance reductions. We believe that the valuation-error results uncovered in the FHA paper indicate that balance-reduction policies face substantial hurdles in actual practice.
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