Martin Feldstein knows recessions. He founded the National Bureau of Economic Research's Business Cycle Dating Committee in 1978. The committee is the official arbiter of when recessions start and stop. (Fed chief Ben Bernanke used to be on the committee.) Feldstein has studied recessions for decades and written numerous papers on them. This is what he said today, according to Bloomberg:

Harvard University economist Martin Feldstein, a member of the group that dates business cycles in the U.S., said the nation has entered a recession that could be the worst since World War II.

``I believe the U.S. economy is now in recession,'' Feldstein, president of the National Bureau of Economic Research, told the Futures Industry Association conference in Boca Raton, Florida. ``Could this become the worst recession we have seen in the post-war period? I think the answer is yes. I would emphasize the word `could.' ''

Feldstein's remarks represent the first time that a member of the NBER's business-cycle dating committee has publicly described the current downturn as a recession. The economy may not respond quickly to Federal Reserve interest-rate cuts, and a package of tax rebates and investment incentives will offer only a temporary boost, he said.