Chapter 22 Input output tables
22.1 The Input-Output (I-O) tables form an integral part of the ASNA. They present a comprehensive picture of the supply and use of all products in the economy, and the incomes generated from production. They also provide a much more detailed disaggregation of gross domestic product than is available in the national income, expenditure and production (GDP) accounts. This chapter provides a detailed description of the I-O tables, their importance within the overall ASNA, the compilation process and how they relate to the rest of the accounts. In national accounting and economic analysis two kinds of I-O tables are referred to:
- Supply and Use (S-U) tables (see Chapter 7 for a full description of how S-U tables are used to benchmark the ASNA); and
- I-O tables, including symmetric I-O tables (product by product or industry by industry matrices which combine supply and use into the one table, with identical classifications of products or industries applied to both rows and columns).
22.2 The integration of 'input-output' in the overall system of national accounts is an important feature of the ASNA. Its role in the ASNA is primarily related to the goods and services accounts and to the shortened sequence of accounts for industries. The I-O tables serve to provide a more detailed basis for analysing industries and products through a breakdown of the production account, leading to the symmetric input-output table. 'Symmetric' means that the same classifications or units (e.g. the same groups of products) are used in both rows and columns. When the number of rows of products and columns of industries happens to be equal, they are referred to as square (not symmetric) I-O tables. However, I-O tables are most often rectangular (having more products than industries).
22.3 The I-O and S-U tables serve two purposes: statistical and analytical. They provide a framework for checking the consistency of statistics on flows of goods and services obtained from quite different kinds of statistical sources - industrial surveys, household expenditure surveys, investment surveys, foreign trade statistics, etc. The ASNA, and the I-O tables in particular, serves as a coordinating framework for economic statistics, both conceptually for ensuring the consistency of the definitions and classifications used and as an accounting framework for ensuring the numerical consistency of data drawn from different sources. The I-O framework is also appropriate for data estimation purposes, and for detecting weaknesses in data quality and estimation. By providing information on the structure of, and the nature of product flows through the economy, the I-O tables assist in the decomposition of transactions into prices and volumes for the calculation of an integrated set of price and volume measures. As an analytical tool, input-output data are conveniently integrated into macroeconomic models in order to analyse the link between final demand and industrial output levels. Input-output analysis also serves a number of other analytical purposes or uses, which are discussed further in the sections below.
22.4 I-O tables are not revised once they have been finalised. They are not compiled as a time series but rather are a point in time reflection of the economy. The rest of the national accounts (e.g. the S-U tables and the GDP accounts) may be revised for all periods whenever an historical revision is undertaken, and therefore are a consistent time series. Therefore, an I-O table can only be considered current with the published national accounts within a year of their publication.
22.5 Various tables are included under the broad heading of I-O tables. Each of these tables provides detail that underlies the aggregates recorded in the gross domestic product account. These summary accounts are focused on the end result of economic activity, whereas the I-O tables provide detailed dissections of that activity, industry to industry flows and by showing intermediate transactions they enhance the description of productive activity within the economy.