A summary of the most important concepts and relationships in national income accounting; for further details consult your notes, text, other handouts, and/or articles. ALL OF THESE EQUATIONS ARE ACCOUNTING IDENTITIES AND MUST HOLD BY DEFINITION.
1. Gross Domestic Product is the annual flow measure of all currently produced final goods and services within the country's borders evaluated at market prices.
Gross National Product is the annual flow measure of all currently produced final goods and services by the country's residents evaluated at market prices.
The difference between them is that GDP measures production by where it is produced (within the nation's physical boundaries), regardless of who (residents or foreigners) produced it; GNP measures production by who produced it (U.S. residents), regardless of where produced (home or abroad).
GNP = GDP + net factor payments from abroad
2. GDP and GNP are measured by three methods: expenditure, income, and value-added (production). Note the conceptual equivalence in measuring output, income, and product; each transaction in the circular flow of macroeconomic activity involves exchange of goods, services, or factors for an equivalent value of revenue or income.
3. Expenditure method: adds the purchases of final goods and services from the four economic sectors, netting-out purchases of final goods and services from abroad (imports):
GDP = C + I + G + (X-M)
With I(net) = I(gross) – Depreciation we have:
NetDP = GDP - Depreciation = C + I(net) + G + (X-M)
NetNP = GNP – Depreciation
NetNP = NetDP + net factor payments from abroad
Then, subtracting indirect business taxes (the portion of firms' sales revenues which do not represent output produced, but are sales and excise tax receipts remitted to the government) and business transfers, and adding net subsidies to government businesses, yields:
National Income = NNP - IBT - business transfers + subsidies to government businesses or
National Income = NDP + factor payments from abroad – IBT - business transfers + subsidies to government businesses
4. Income method: the sum of payments or claims (income) earned by
a) compensation to employees b) corporate profits
c) proprietors' income d) net rental income
e) net interest payments to households
The NI earned by households must be disbursed as C + S + T.
(Note: Depreciation is regarded as being offset by some household saving to replace worn-out capital stock and IBTs are regarded as some taxes paid indirectly by households; if the "other" adjustments are ignored, then conceptually National Product = National Income in either gross or net terms.)
5. Value-added method: the value of the gross production by firms minus the cost of produced inputs; doing so avoids double-counting the value of produced inputs. This net difference is the firm's value-added produced and the sum of value-added is GDP.
6. Personal Income and Disposable Personal Income are two other conceptual income measures frequently reported and used.
PI = NI less earned payments not paid to households (savings or taxes remitted for them by firms) plus transfers paid to households (income not earned, but payments nonetheless received and available to households).
Thus, PI = NI - corp. profits taxes - undistributed corp. profits (retained earnings) - soc. sec. contribs. + gov. and bus. transfers to households + net gov. interest. PI is more closely the actual income households receive.
DPI is PI less income taxes and other payments that must legally be made by households:
DPI = PI - personal taxes - non-tax fees.
DPI is the income households have available to spend on consumption or hold as personal savings.
7. To make it easier for some analyses, these accounting measures are simplified further by making two assumptions. They are: 1) ignore depreciation, IBT, and "other" adjustments and 2) all factor payments earned are actually paid to households. That is, firms do not pay taxes (no business taxes and all taxes are paid by households), there are no business transfer payments to households, and firms distribute all profits to households (no business savings and all savings is done by households).
With these assumptions:
GDP = NDP = NI = PI = Y. (Y will denote income, product, or output interchangeably.)
Thus: C + I + G + X-M = Y = C + S + T and then
I + G + X-M = S + T rearranging
I - S + (G - T) + (X-M) = 0 or
I + (G - T) + (X-M) = S or
I = S + (T - G) + (M - X)
Note that the relationship must hold among these balances.