Negli Stati Uniti l'indice di riferimento è l'indice S&P Case-Shiller. In questo caso l'evidenza dalla serie storica (che potete trovare gratuitamente dall'eccellente database pubblico di serie storiche mantenuto dal Shiller sulla sua homepage a Yale, cliccate qui) suggerisce che i prezzi delle case non aumentino in media nel tempo più velocemente dell'indice dei prezzi al consumo. In questo caso
house prices may still be overvalued by something like 30 percent. That’s roughly the gap between average household income growth and inflation over the last generation.
It’s also the overvaluation suggested by Mr. Shiller’s historical index. Today, it is around 130, which is way down from the 2006 bubble peak of 203. But it’s still far above the 1890 to 1970 average of 94.
In effect, the bears are arguing that housing was in a multidecade bubble and has now entered a multidecade slump.
Ma uno spiraglio di luce potrebbe venire da chi, come lo stesso Case ed altri analisti, sostiene che i prezzi delle case crescono al ritmo della progressione dei redditi delle famiglie, deducendone la fine della bolla immobiliare. Scrive il NYTimes:
This side can also make a case based on history. Mr. Case points out that all pre-1970 housing statistics are suspect. By necessity, Mr. Shiller’s oft-cited historical index is a patchwork that relies on several sources, like Labor Department surveys. These sources happen to paint a more negative picture of past house prices than some other data.
For example, the Census Bureau has been asking people since 1940 how much they think their houses are worth, as Mr. Lawler noted in one of his newsletters. The answers suggest that house values rose faster than general inflation — and about as fast as incomes — not just from 1970 to 2000, but from 1940 to 1970, as well.
Likewise, Mr. Case has dug up sales records for houses in the Boston area that were built in the late 19th century and are still around. The records show prices rising 2.5 percentage points a year faster than inflation, which is just about what income has done.
Perhaps most persuasive is a statistic that Mr. Shiller sent me when I asked him about this debate. It shows that the share of consumer spending — and, by extension, of income — devoted to housing has not fallen over time. It has hovered around 14 or 15 percent for the last 60 years. The share of spending devoted to food, by contrast, has dropped to 13 percent, from 25 percent.
These numbers make a pretty strong argument that the post-1970 period is not one long aberration. As societies get richer, they do spend more and more on housing.
Mi trovo istintivamente d'accordo con le conclusioni dell'analisi:
The best advice for homeowners and would-be buyers may be to think of a house not as an investment, first and foremost, but as a place to live. If there is a good chance you will move in the next three years or so, you should probably rent. The hassles of buying and the one-time costs are just too big. Plus, house prices are not low in most places today.
The ratio of median house price to income is about 3.4, compared with a prebubble average of about 3.2. Given the economy’s weak condition and the still high number of foreclosures, prices may well fall more in the next year or two. They look especially high in places where rents are comparatively cheap, like San Diego and San Francisco. And maybe income growth will remain weak for years, holding down home-price growth.
But if you can imagine staying much longer than a few years, you should take some comfort in the fact that the bubble seems mostly deflated. Sometime soon, prices should begin rising again. They may not quite keep up with incomes, but they will probably outpace the price of food and clothing.
Now, if only it were possible to be as sanguine about the economy’s other problems.