Take, say, most of this year. If it has felt like a recession to you, you're not alone.
Alan Greenspan, a former Federal Reserve chairman, said after Bear Stearns collapsed in March that "the current financial crisis in the U.S. is likely to be judged as the most wrenching" since the end of World War II. And Harvard professor Martin Feldstein, former head of the National Bureau of Economic Research, said that month he believed the country was in a recession that could be severe.
Here are some questions and answers about how a recession is declared:
Q: Who decides when a recession has begun?
A: The National Bureau of Economic Research, a private, nonprofit research organization, is the arbiter of recessions.
The group, founded in 1920, has more than 1,000 university professors and researchers who act as bureau associates, studying how the economy works. Sixteen of the 31 American Nobel Prize winners in economics and six of the past chairmen of the president's Council of Economic Advisers have been NBER researchers.
The group's Business Cycle Dating Committee makes the call on recessions. The small committee
- recently it had only seven members - is made up of experts on the economic peaks and valleys that comprise expansions and recessions.
Q: What qualifies as a recession for the NBER?
A: The NBER's definition of a recession is a significant decline in economic activity spread across the economy, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production and wholesale and retail trade.
GDP - short for gross domestic product - is a measure of the value of all goods and services produced within the United States.
A recession's start and end dates are based on the high and low points within the nation's "business cycle"
- periods of economic growth and contraction. A recession begins when the economy peaks at the top of an expansion period. It continues as the economy contracts until it hits the "trough," the lowest point in the downward cycle. After that, the economy begins to recover. The "peak" date is the beginning of a recession and the "trough" date is its end.
The last official recession began when the economy peaked in March 2001. It lasted eight months, ending in November 2001, when the economy hit its bottom for that business cycle. Previously, the economy had expanded for 10 years.