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The input-output context
9.7 In national accounting and economic analysis two kinds of input-output tables (or matrices) are referred to:
9.8 The S-U tables are sometimes referred to as rectangular input-output tables, make and use tables, supply and disposition of products, etc. In the ASNA, the term 'S-U tables' is used. The symmetric input-output tables are also often termed 'square' (input-output) tables or matrices, Leontief-type input-output tables (matrices), etc. The square symmetric tables are either product-by-product or industry-by-industry. In this chapter the term 'tables' is used rather than 'matrices', and the terms 'product-by-product' tables and 'industry-by-industry tables' are used to describe tables in which the rows and columns both relate to products, or industries, respectively.
9.9 The concepts and definitions in the S-U tables are the same as elsewhere in the ASNA.
9.10 The S-U and input-output tables also adopt the accounting rules of the ASNA, i.e. the definitions, conventions, etc., which are employed with respect to transactions and transactors apply equally to the input-output framework.
9.11 Issues of particular importance to the input-output tables include:
both of which are discussed below.
Statistical units for input-output
9.12 Institutional units may engage in several different kinds of productive activities simultaneously. For the detailed analysis of production, the system therefore recommends that they should be partitioned into separate establishments, each of which engages in only a single kind of productive activity at a single location. Industries are then defined as groups of establishments engaged in the same kind of productive activities. Ideally, the industries in the system would be composed of establishments that are homogeneous production units.
Principal, secondary and ancillary activities
9.15 When an establishment engages in more than one kind of activity, by reference to a given classification of activities, it is necessary to observe the fundamental distinction between principal and secondary activities on the one hand and ancillary activities on the other:
9.16 The establishment unit used for the sequence of accounts for industries may include principal as well as secondary productive activities within it, although secondary activities should be separated as far as practically possible. The further treatment of secondary production is one of the central issues met in the construction of symmetric input-output tables.
9.17 Ancillary activities typically produce outputs of services which are used as inputs into almost all kinds of productive activities, and their values are likely to be small compared with those of the principal and secondary activities of the enterprise. Consequently, they are treated as integral parts of the principal or secondary activities with which they are associated. In a production account and input-output context, ancillary activities are treated as follows:
9.18 In addition, output of an industry may include more than a single product when two or more products are produced simultaneously by a single productive activity as 'joint products' (e.g. molasses linked to the production of sugar; natural gas linked to crude oil). Joint products may be distinguished as the principal product (by largest proportion) and the by-product (or by-products). In practice, by-products are often treated in the same way as secondary products in the input-output framework.