As part of the promotion for the Stanley Kubrick/Steven Spielberg movie A.I., Dreamworks created an ingenious online game that had Internet cybersleuths trying to solve a murder mystery. The puzzles were extremely complicated -- and unlikely to ever be solved by just one person. So, thousands of people banded together, using their expertise, knowledge, and insight to solve the puzzles and the mystery.

To quote Bill Cosby: "I told you that story so I could tell you this story..."

One of the most impressive things that occurs when I write on certain subjects, notably anything on the New York Times' editorial page, is the feedback I get from readers. Let me first note that I never intend or allow anyone "to get away with" whatever statement they've made. It's possible, indeed probable, that I don't know a particular statement is false or misleading. I don't know everything, but combined, all of the readers out there in the blogosphere do.

In the interest of completeness of criticism of Paul Krugman and his Friday column, I received the following letter from a reader:

Good dissection of Krugman's prattle today, but you allowed him to get away with repeating a fiction that's understandable for a non-economist to make, but for a macroeconomist it's positively embarrassing.

Krugman wrote: "...the milder oil price spike before the gulf war was also followed by a recession."

That's simply false. The recession of 1990-1991 began *before* Saddam Hussein invaded Kuwait in August. There was an oil price shock during the invasion and war, but it did not prevent the recession from ending in March 1991, the same month the Gulf War ended.

It's an easy mistake to make because by the time we figure out we're in a recession, we've been in it for a while. In 1991 and 1992, the popular myth was that there was still a recession, because economists were looking back at the end of 1990. Furthermore, unemployment is a *lagging* economic indicator, meaning that it reaches its peak many months after GDP growth bottoms out. Unemployment was high in 1992, but that was a result of the recession of a year before that had ended. That didn't mean that the recession was still going on. Krugman shouldn't be making this mistake, one that no introductory macroeconomics student would. He should be incapable of it, yet for an economic titan, he sometimes has trouble with adding and subtracting.

Information on the dates of US recessions can be found here.

And now the record is complete.