Frequently Asked Questions

For policymakers and businesses to better understand the economy and to formulate appropriate policies, up-to-date and accurate estimates of gross domestic product (GDP) are essential. BEA’s earliest GDP estimate—the “advance” estimate—is released roughly four weeks after the end of each quarter. The second and third estimates—which are released over the next two months—incorporate progressively more complete and more accurate source data as they become available from the Census Bureau, the Bureau of Labor Statistics, and other sources. 

In addition, BEA produces annual revisions of the GDP estimates that incorporate more accurate and detailed annual source data. And roughly every 5 years, BEA produces benchmark revisions of the GDP estimates, which incorporate various updates in methodologies and classifications as well as source data from the Census Bureau’s decennial and quinquennial economic censuses, considered among the highest quality statistical data.

An overview of BEA’s revision processes and the source data are described in “Taking the Pulse of Economy: Measuring GDP,” by J. Steven Landefeld, Eugene P. Seskin, and Barbara M. Fraumeni in the Spring 2008 issue of the Journal of Economic Perspective. BEA methodologies for the national accounts are described in detail in Concepts and Methods of the U.S. National Income and Product Accounts on the BEA Web site.

While there is always a trade-off between timeliness and accuracy, BEA believes that the early GDP estimates have struck an appropriate balance, as the magnitude of the revisions to the early estimates tends to be small. A recent study published in July 2011 Survey of Current Business found the following:

• The revisions to long-term growth rates are small, averaging less than 0.1 percentage point for average growth rates over the comprehensive benchmark revisions between 1985 and 2009.
• There are no substantial revisions—as measured by the shares of GDP or GDI—to key measures, such as investment and government expenditures or the national saving rate.
• The revisions to the contributions of key components of GDP growth are small and do not substantially change the ordinal rankings of the components’ contributions to growth over expansions and contractions.
• The overall pattern of change in GDP over business cycles is little changed by the revisions (see charts 1 and 2 below).

The study also found that the three early quarterly estimates provide an accurate picture of trends, contributions, high versus low growth, and accelerating versus decelerating growth.

More information on the 2011 annual revision of the national income and product accounts is available at www.bea.gov.

The following charts were based on GDP data that were published before the release of the 2011 annual revision of the national economic accounts on July 29, 2011.