COMMODITY BALANCES AND NATIONAL ACCOUNTS: A SAM PERSPECTIVE

This paper is concerned with the treatment of commodity and activity balances in a national accounts context. It makes use of a general method for reducing the size of a social accounting matrix (SAM) by apportioning the elements of one or more accounts to the rest. The national accounts are looked at in terms of their usefulness for policy analysis, not least analysis of the impact of price changes. The SNA convention of separately distinguishing activities and commodities is endorsed. However, in contrast to the SNA, it is argued that for analytic purposes commodity transactions should be recorded at market prices, with a separate account for each of the markets for a given commodity in which a distinct price prevails. The SNA SAM is shown to be a reduced form of the SAM resulting from this recommended treatment of commodity transactions, while a further round of reductions (apportionments) yields SAMs which are familiar from input-output analysis, in which activities and commodities are not separately distinguished. It is argued that no special effort would be required to produce SAMs in which commodity balances are recorded at market prices as recommended here (the necessary data are also required to produce the conventional SNA tableaux), and that all reduced form versions of such SAMs, including the SNA, are inferior as a basis for the analysis of price effects on the structure of production.