Here are some basic concepts about GDP that you should already know. Getting GDP data without a basic understanding of national income accounting is dangerous and should not be attempted. Use the list below as a quick refresher of your knowledge of GDP. Gross Domestic Product (GDP) is the market value of all final goods and services produced within a country in a given period of time. GDP is a flow not a stockit measures output per time period, not a total accumulated at a point in time. GDP = C I G NX. This fundamental equation expresses the fact that GDP can be computed as the sum of Consumption (C), Investment (I), Government spending (G), and Net Exports (NX). There are two other ways to compute GDP: (1) the income approach: sum the payments received by every factor of production and (2) the product approach: count every final good and service produced, multiply by its price, and sum. The three ways are equivalent in theory, but there are statistical discrepancies in practice. A circular flow diagram shows that GDP can be interpreted as both output and income; these are two sides of the same coin. C, I, and G