UN DESA | DPAD | Development Policy Analysis Division
Social Accounting Matrices
A Social Accounting Matrix (SAM) is a square matrix in which each account is represented by a row and a column. It provides a comprehensive picture of the economic transactions of an economy. Each cell shows the payment from the account of its column to the account of its row. Thus, the incomes of an account appear along its row and its expenditures along its column. For each account in the SAM, total revenue (row total) should be equal to total expenditure (column total). It should be noted that SAMs almost invariably are limited to flows; additional data or assumptions are needed to define stocks. Due to its accounting consistency and comprehensiveness in recording data, the SAM has become the preferred tool to calibrate computable general equilibrium (CGE) models—such as MAMS: that is, they are useful to define base-year values for most endogenous variables as well as compute most of the structural parameters of the model.
A number of capacity-development projects implemented by DPAD have produced SAMs for different countries. Depending on the project, the SAMs have unconventional features that made them more adequate to calibrate the models used. Each country's specific SAM includes a standard version and a more "unconventional" version that has been adapted for a particular model.
SAMs for MAMS
SAMs have been constructed and adapted to calibrate the Maquette for MDG simulation (MAMS)—a dynamic computable general equilibrium (CGE) model. MAMS includes a special module for the "production" of services associated with the Millennium Development Goals (MDGs) and, as such, it is a model that requires calibration with an "unconventional" SAM with the following salient features: separate accounting of interest payments to domestic institutions and the rest of the world; inclusion of a capital account per institution; and specification of accounts for investment by sector of destination, among others.