Gross domestic product
Gross domestic product (GDP) is a monetary measure of the market value of all the final goods and services produced in a period of time, often annually 
GDP (nominal) per capita does not, however, reflect differences in the cost of living and the inflation rates of the countries; therefore using a basis of GDP per capita at purchasing power parity (PPP) is arguably more useful when comparing differences in living standards between nations.
Twin deficits hypothesis
where "Y" represents national income or GDP, "C" is consumption, "I" is investment, "G" is government spending and "X–M" stands for net exports. This represents GDP because all the production in an economy (the left hand side of the equation) is used as consumption ("C"), investment ("I"), government spending ("G"), and goods that are exported in excess of imports ("NX"). Another equation defining GDP using alternative terms (which in theory results in the same value) is