Regional Social Accounting Matrices, or SAM, represent an IMPLAN extension for regional Input-Output modeling. The SAM provides information on non-market financial flows. IMPLAN inter-industry models provide information on market transactions between firms and consumers, and they capture payments of taxes by individuals and businesses, transfers of government funds to people and businesses, and transfer of funds from people to people.

IMPLAN Group, LLC has developed methodologies for creating local (county) area SAM data that is consistent with Bureau of Economic Analysis' National Income and Produce Accounts (NIPA).
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SAM Framework

Like Input-Output (I-O) tables, a full SAM is a double-entry bookkeeping system capable of tracing monetary flows between industries through debits and credits similar to T-Accounts in basic financial accounting. SAMs extend traditional I-O accounts by also providing information on non-market financial flows - i.e., industry-institution transfers and inter-institution transfers.

The matrix format allows the double-entry bookkeeping to be displayed in a single entry format. The column entries represent expenditures (payments) made by the economic agents. The row entries represent receipts or income to agents. By accounting definition, all receipts must equal all expenditures. That is, the SAM must balance. The shaded areas in Figure 24-1 are the inter-institutional (non-industry) transfers cells.

Column and row entries represent different economic actors. Across the row, "Industry" represents Industries producing goods and services. "Commodity" is the goods and services consumed by Industries and Institutions. "Factors" are factors of production, such as Employee Compensation, Proprietors Income, and Other Property Income. "Institutions" include Household and government accounts. "Capital" is investment and borrowing. "Enterprises" represent the distribution of corporate profits. "Trade" (exports and imports) show monetary flows into and out of a region.

Individual elements within the SAM tables include the use and make matrices and Value Added. The use table shows the use of Commodities by Industry or the goods and services required to produce an Industry's output. The make table shows the make of Commodities by Industry, or who produces Commodities. These are typical components of Input-Output models. Also found in typical I/O models are final demand or Institutional consumption, exports, and imports.

The SAM adds non-industrial financial flows in addition to the typical I/O elements. Looking first at receipts or income, Industries make payments to Commodities for goods and services, payments to workers, profits (factors), payments to Institutions (households, governments, capital) or distributions, taxes, and borrowing. Lastly, Industries make payments to imports for use in production. The total is Total Industry Outlay.

Commodities make payments in the sense that there is a sum paid to produce Commodities. There are also non-Industrial production of Commodities from Institutions.

Institutional income is also distributed to other Institutions. This is the real contribution of a SAM. These inter-institutional transfers show the flow of non-industrial funds. Inter-institutional transfers include transfers from businesses to households (interest and dividend payments), transfers from people to government (payment of taxes), and transfers from governments to people (social security, unemployment compensation, and other refunds and benefits). Inter-institutional transfers also include the capital accounts. For businesses, this is investment and borrowing. For households, this is net savings. Government capital accounts show surplus and deficits.