Business cycle dating
To identify the start of the great recession they needed to identify a peak.
The NBER “emphasizes economy-wide measures of economic activity.
During a recession, a significant decline in economic activity spreads across the economy and can last from a few months to more than a year.Its main conclusion is that since the last trough in 2013Q1, the euro area has been recovering at a slow but steady pace.This post-recession recovery is commensurate with that of the US recovery, considering it began later, after the double-dip European recession that followed the global financial crisis. Since then there have been five complete cyclical episodes (recession followed by expansion).The committee believes that domestic production and employment are the primary conceptual measures of economic activity.” and “believes that the two most reliable comprehensive estimates of aggregate domestic production are normally the quarterly estimate of real Gross Domestic Product and the quarterly estimate of real Gross Domestic Income, both produced by the Bureau of Economic Analysis.