SEMAINE D'ÉTUDE SUK LE ROLE DE L ANALYSE ECONOMETKIOUE ETC. 1237

characteristic for these sectors that their production need not
be equal to their disappearance into national final demand and
Inter-sectoral deliveries. It is by manoeuvring with the productive
 capacities of these sectors that the economy must try
to attain the highest comparative advantages, that is, to maximize
 national product — maybe within limits set by regional
policy. As another simplification the transportation costs of the
oroducts of these sectors may be neglected.

7. It seems proper to use the method of input-output analysts
 for the description of the necessary inter-sectoral deliveries.
Occasionally choices between alternative production processes
may have to precede and for some particularly important cases
even to be built in into the model making it a linear programming
 model. It is characteristic for the subdivision of an economy:
 into regions that there may be relevant differences in
production costs of the same commodity between regions. This
will translate itself into differences between one or more of the
input coefficients for the corresponding sector. This may simplify
 itself up to the point where production in some sectors is
only possible in a limited number of regions, a good example
being mining or energy. We do not call such a sector a regional
sector, as the reader might suppose; its product will serve many
regions.

In some sectors indivisibilities may play a relevant role:
this is true for irrigation, energy and heavy industries. It
may be important for some services including university education.
 We may follow one of two ways of representing this
feature: either we may assume a minimum value for investments
 to be made in such a sector, or we may assume curvilinear
 relations such as the well-known .6™ power of production
determining investment inputs. The latter approach cannot
be chosen too often if we do not want to make the system of
equations unmanageable.

ol Tinbergen - pag.

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