1. Introduction
The Social Accounting Matrix (SAM) is a square matrix and can be considered as an organized
framework that presents a set of accounts between and within which the flows of funds (or the
nominal flows) represent the circular flows of income in a market economy.
By convention, the entries made in rows represent resources, incomes, receipts or changes in
liabilities and net worth, whilst the entries made in columns represent uses, outlays, expenditures or
changes in assets, each transaction being recorded only once in a cell of its own. These figures will
include both production and institutional accounts, which are further subdivided into yet other
accounts, defined in accordance with the goal of the study and the available information.
The National Accounting Matrix (NAM)1 is also a square matrix that can be considered as an
organized framework of the national accounts, whose similarity with the SAM makes it possible to
construct one matrix from the other, as shown in this paper. Consideration will be given here to the
1993 version of the United Nations System of National Accounts - SNA 93, prepared by the Inter-
Secretariat Working Group and published by the United Nations Statistical Office (ISWG, 1993),
and its application to the European Union through the European System of National and Regional
Accounts in the European Community of 1995 - ESA 95 (Eurostat, 1996).
Although the NAM is sometimes referred to as a SAM, the NAM presented here will be the one
that is presented in chapter XX of SNA93, (ISWG, 1993) and Prgs.8.133 - 8.155 of ESA 95,
(Eurostat, 1996) and the SAM will be the one developed from the work of Graham Pyatt and his
associates (Pyatt, 1988 and 1991; Pyatt and Roe, 1977; Pyatt and Round, 1985), inspired upon Sir
Richard Stone’s works, pioneered by his 1954 article “Input-Output and the Social Accounts”.
Each SAM can be expressed in two versions: numerical and algebraic. In the numerical version,
each cell assumes a specific number value, the sums of the rows being equal to the sums of the
columns. In the algebraic version, each cell is represented by an algebraic expression that, together
with those of all the other cells, represents a SAM-based model, the calibration of which depends
upon the replication of the numerical version.
Therefore, the numerical version needs to be a good one in order to be able to support good models,
the Computable General Equilibrium (CGE) models being considered particularly appropriate for
operating with a SAM framework (Abbink et al., 1995).
On the one hand, Section 2 of this paper will show the similarity between the SAM and the NAM,
explaining how to pass from one to the other, while, on the other hand, using an example for
Portugal, it will show how the SAM could be implemented in the European Union.
1 Expression adopted from Keuning (1991).