There is no fixed rule about what weights the committee assigns to the various indicators, or about what other measures contribute information to the process.
Rather, the committee determined only that the recession ended and a recovery began in that month.
A recession is a period of falling economic activity spread across the economy, lasting more than a few months, normally visible in real GDP, real income, employment, industrial production, and wholesale-retail sales.
The committee places less emphasis on monthly data series for industrial production and manufacturing-trade sales, because these refer to particular sectors of the economy.
Movements in these series can provide useful additional information when the broader measures are ambiguous about the date of the monthly peak or trough.
The committee decided that any future downturn of the economy would be a new recession and not a continuation of the recession that began in December 2007.
The basis for this decision was the length and strength of the recovery to date.The trough dates for these indicators are: Macroeconomic Advisers' monthly GDP (June) The Stock-Watson index of monthly GDP (June) Their index of monthly GDI (July) An average of their two indexes of monthly GDP and GDI (June) Real manufacturing and trade sales (June) Index of Industrial Production (June) Real personal income less transfers (October) Aggregate hours of work in the total economy (October) Payroll survey employment (December) Household survey employment (December) The committee concluded that the choice of June 2009 as the trough month for economic activity was consistent with the later trough months in the labor-market indicators–aggregate hours and employment–for two reasons.First, the strong growth of quarterly real GDP and real GDI in the fourth quarter was inconsistent with designating any month in the fourth quarter as the trough month.Further, macroeconomic indicators are subject to substantial revisions and measurement error.For these reasons, the committee refers to a variety of monthly indicators to choose the months of peaks and troughs.The committee waited to make its decision until revisions in the National Income and Product Accounts, released on July 30 and August 27, 2010, clarified the 2009 time path of the two broadest measures of economic activity, real Gross Domestic Product (real GDP) and real Gross Domestic Income (real GDI).