Put simply, GDP is a broad measurement of a nation’s overall economic activity. Source: Investopedia.com
Now here’s an economic indicator that can say “one thing one minute” and then revise it (the numbers) at some future date. And, it’s OK to do so… GDP is an example of an economic indicator that can be and “is” revised or adjusted after its “numbers have been officially released by the U.S. Department of Commerce, Bureau of Economic Analysis. Revisions to GDP are expected as a matter of course because the very nature of the GDP calculation is the summary of many different aspects of the national economy.
Investopedia.com has a very short video that explains the calculation of GDP.
Here’s a link to CNBC announcing a second quarter revision to the second quarter 2015 GDP report. It’s an example of how complicated the GDP measurement really is to calculate.
The GDP calculation tries to determine “are we, as a nation, growing or not”. Is our economy expanding or contracting at a particular point in time.
Indicator Name: Gross Domestic Product (GDP)
Published by: U.S. Department of Commerce, Bureau of Economic analysis
Publishing Calendar: Monthly with revision releases as needed or necessary
Author’s Addendum (9/13/2015): CNBC has a nice summary of the function of GDP written by Mark Koba, see Gross Domestic Product: CNBC Explains.
Rationale for the By the Numbers blog postings.