Input-Output Matrix
Contents
Definition
The Industry Transaction Matrix (or Transactions Table) is the fundamental quantitative information used in Input-Output Analysis. It concerns the flow of products from each industrial sector (considered as a producer) to each of the sectors, itself and others (considered as consumers).[1]
Formula
The transaction matrix is usually denoted as
Single Region Case
If there are n sectors in an economy the matrix reads:
- The entries of the matrix may denote either monetary values (in some defined currency) or physical (activity) values, e.g. volumes.
- The matrix is a flow matrix, hence values refer to a particular time period.
Multi-Regional Case
In the case of a Multiregional Input-Output Model where industrial sectors operate within distinct "regions" (e.g., countries) the transactions data are most conveniently expressed as a Tensor that captures exchanges between sector i and j located in regions p and q respectively.
In practice this tensor of rank four is represented as a "rolled-out" as a Partitioned Matrix[2] under the assumption that there is a global transactions matrix, in other words, regions and sectors are merely labels for production units that are qualitatively of similar nature.
Usage
This basic information from which an input-output model is developed is contained in an inter-industry transactions table. The rows of such a table describe the distribution of a producer’s output throughout the economy. The columns describe the composition of inputs required by a particular industry to produce its output.
The Transaction Matrix is of fundamental importance and may underpin alternative possible input-output models.