Real versus nominal value (economics)
Gross domestic product (GDP) is a measure of aggregate output. Nominal GDP in a particular period reflects prices which were current at the time, whereas real GDP compensates for inflation. Price indices and the U.S. National Income and Product Accounts are constructed from bundles of commodities and their respective prices. In the case of GDP, a suitable price index is the GDP price index. In the U.S. National Income and Product Accounts, nominal GDP is called "GDP in current dollars" (that is, in prices current for each designated year), and real GDP is called "GDP in [base-year] dollars" (that is, in dollars that can purchase the same quantity of commodities as in the base year).
Tendency of the rate of profit to fall
Not only are GDP data frequently revised after first publication, but the popular idea that GDP equals "the whole economy" is a fallacy. It is a fallacy, not just because intermediate items, transfers and net factor income from abroad are excluded, but also because more domestic assets, incomes, transfers and spending exist beyond the defined "production" boundary for Gross Output (including, importantly, activities of government, financial institutions/companies, and households).