Gross domestic product (GDP) is a monetary measure of the value of all final goods and services produced in period of time (quarterly or yearly). GDP estimates are commonly used to determine the economic performance and standard of living of a whole country or region, and to make international comparisons.
GDP is not a complete measure of economic activity. It accounts for final output or value added at each stage of production, but not total output or total sales along the entire production process. It deliberately leaves out business-to-business (B2B) transactions in the early and intermediate stages of production, as well as sales of used goods. In the United States, the Bureau of Economic Analysis (BEA) has introduced a new quarterly statistic called gross output (GO), a broader measure that attempts to add up total sales or revenues at all stages of production. Mark Skousen was the first economist to advocate GO as an important macroeconomic tool. Other countries are following suit, such as the United Kingdom, which now producing an annual statistic called Total Output.
GDP attempts to measure the “use” economy, i.e., the value of finished goods and services ready to be used by consumers, business and government. GDP is similar to the “bottom line” (earnings) of an accounting statement, which determined the “value added” or the value of final use. GO is an estimate of the “make” economy, i.e., the monetary value of sales at all stages of production. Thus, GO is similar to the “top line” (revenues or sales) of an accounting statement. GDP and GO are not mutually exclusive, but complementary ways to examine what’s happening in an economy.
As Dale Jorgenson, Steve Landefeld, and William Nordhaus conclude in “Gross output () is the natural measure of the production sector, while net output () is appropriate as a measure of welfare. Both are required in a complete system of accounts.”
The OECD defines GDP as "an aggregate measure of production equal to the sum of the gross values added of all resident, institutional units engaged in production (plus any taxes, and minus any subsidies, on products not included in the value of their outputs).” GDP by Industry can also measure the relative contribution of an industry sector. This is possible because GDP is a measure of 'value added' rather than sales; it adds each firm's value added (the value of its output minus the value of goods that are used up in producing it). For example, a firm buys steel and adds value to it by producing a car; double counting would occur if GDP added together the value of the steel and the value of the car. Gross output (GO) measures sales at all stages of production and therefore involves some degree of “double counting.” Because it is based on value added, GDP also increases when an enterprise reduces its use of materials or other resources ('intermediate consumption') to produce the same output. The more familiar use of GDP estimates is to calculate the growth of the economy from year to year (and recently from quarter to quarter). The pattern of GDP growth is held to indicate the success or failure of economic policy and to determine whether an economy is 'in recession'.
William Pretty came up with a basic concept of GDP to defend landlords against unfair taxation during warfare between the Dutch and the English between 1652 and 1674.〔(【引用サイトリンク】url=http://www.economist.com/news/finance-and-economics/21591842-meet-sir-william-petty-man-who-invented-economics-petty-impressive )〕 Charles Davenant developed the method further in 1695. The modern concept of GDP was first developed by Simon Kuznets for a US Congress report in 1934.〔Congress commissioned Kuznets to create a system that would measure the nation's productivity in order to better understand how to tackle the Great Depression.Simon Kuznets, 1934. "National Income, 1929–1932". 73rd US Congress, 2d session, Senate document no. 124, page 5-7 Simon Kuznets, 1934. "National Income, 1929–1932". 73rd US Congress, 2d session, Senate document no. 124, page 5-7
Simon Kuznets, 1934. "National Income, 1929–1932". 73rd US Congress, 2d session, Senate document no. 124, page 5-7. https://fraser.stlouisfed.org/scribd/?title_id=971&filepath=/docs/publications/natincome_1934/19340104_nationalinc.pdf
〕 In this report, Kuznets warned against its use as a measure of welfare (see below under ''limitations and criticisms''). After the Bretton Woods conference in 1944, GDP became the main tool for measuring a country's economy. At that time Gross National Product (GNP) was the preferred estimate, which differed from GDP in that it measured production by a country's citizens at home and abroad rather than its 'resident institutional units' (see OECD definition above). The switch to GDP was in the 1980s.
The history of the concept of GDP should be distinguished from the history of changes in ways of estimating it. The value added by firms is relatively easy to calculate from their accounts, but the value added by the public sector, by financial industries, and by intangible asset creation is more complex. These activities are increasingly important in developed economies, and the international conventions governing their estimation and their inclusion or exclusion in GDP regularly change in an attempt to keep up with industrial advances. In the words of one academic economist "The actual number for GDP is therefore the product of a vast patchwork of statistics and a complicated set of processes carried out on the raw data to fit them to the conceptual framework."
Angus Maddison calculated historical GDP figures going back to 1830 and before.
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