Tuesday, February 21, 2012

How much was 2009 USA GDP?

For some one looking for statistical data about USA, the labyrinth of different sources of official data can be disturbing.
For instance, let’s try to find GDP, current prices, 2009 and its structure by industry.
US Census Bureau provides a table in the Statistical Abstract (here for 2012 edition, see table 670, released last September 2011): 2009 GDP is 14119 b.USD and manufacturing contributes with 1585 (11.2%). All industries is private industries minus agriculture, forestry, fishing and hunting: 12063, which means manufacturing is 13.1% of all industries value added. “All industries” appears often, specially in US Census data, and it means all sectors of the economy unless “agriculture, forestry, fishing, hunting”, and all government services and activities. According to previous data, “all industries” is the non farm private sector of the economy, and it means 89% of the economy. The remaining 11% are basically government: farm related business (agriculture, forestry, fishing, hunting) only contribute with 1%.

When we compare it with the estimates of 2009 ASM Annual Survey of Manufactures (here, see “Statistics for Industry groups and industries”), we get very different numbers per industry. From the estimates of each industry, manufacturing value added should have been 1976, a 26% higher estimate than the previous one (1585). Important differences per industry can be found when comparing table 670 (2009) with 2009 ASM estimates for value added per industry.
But BEA Bureau of Economic Analysis source about industry economic accounts (here) gives different numbers: 2009 GDP was 13939, manufacturing value added was 1540 (11% GDP) and all industries should have been 11878 (manufacturing = 13%). Detail per industry is available and can be compared with the previous two sources.

 We can also have a look at the 2011 Economic Report of the President (table B-12). GDP for 2009 was 14119, manufacturing 1549 and all industries 12063. The same values of US Census Bureau.
What if we look for an outside source? OECD Stat.Extracts for instance. USA GDP was 14119 in 2009 (the same as US Census), and manufacturing value added was 1733 (12.2% GDP, a different value from US Census). From OECD data we estimate “all industries” by GDP minus farm business minus government: 10349 (to be confirmed). GDP numbers are also available from IMF World Bank (World Economic Outlook, 2011 edition). For USA, 2009, value is 12703.

Next table provides the structure of manufacturing added value, by industries, from 2009 ASM (US Census) and BEA (Annual Industry Accounts) (b.USD and %):

Confused? Me too …
Different methodologies, different definitions and the revisions process may explain the differences. 
Macroeconomic data are estimates of an associated variance (error). Not exact numbers. So differences are not very relevant and significant. Different estimates tell a similar “story” in this case. But when comparing between different countries, industries, … that can be important - the same source must be used to guarantee homogeneity of data criteria.

(Update, 1 April: a good guide to these issues is available from BEA: "A guide to national income and product accounts of the United States")

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