Can a controlled experiment explain why people like Kewpie dolls in one year, Beanie Babies in another, and American Girl dolls this year? Yet social scientists are asked to answer analogous questions. We economists and perhaps psychologists shouldn't overreact to the derision. That is, we shouldn't try to overlay a false sense of precision on our admittedly squooshy work.

A major boom in real stock prices in the US after Black Tuesday brought them halfway back to 1929 levels by 1930. This was followed by a second crash, another boom from 1932 to 1937, and a third crash. Speculative bubbles do not end like a short story, novel, or play. There is no final denouement that brings all the strands of a narrative into an impressive final conclusion. In the real world, we never know when the story is over.

In the short run and for decisions unlikely to have broad impact, it may be more cost effective to use just one expert.

The good news is that, at least in economics, I've seen movement away from its overemphasis on mathematical models of purely rational behavior to a more eclectic and commonsense approach: research that is, among other things, more respectful of insights from psychology.

Economists who adhere to rational-expectations models of the world will never admit it, but a lot of what happens in markets is driven by pure stupidity - or, rather, inattention, misinformation about fundamentals, and an exaggerated focus on currently circulating stories.

I am worried that the collapse of home prices might turn out to be the most severe since the Great Depression.

News media stimulate bubbles, since stories about them boost their audience.