SEMAINE D'ÉTUDE SUR LE ROLE DE L’ANALYSE ECONOMETRIQUE ETC. 675

inputs, and these are expressed in the same terms independently
of the industry in which they are used. Similarly, a sudden shift
taking place at the level of a particular technical process in
the origin of one of the inputs (for example a shift in the provenance
 of a fibre from the textile industry to the chemical
industry) means that less labour than before is required to
produce it through the new channel. A shift of this type changes
an inter-industry relation by causing the disappearance of a
coefficient (and of the correspondent variable) and the appearance
 of another, different, one. In the vertically integrated
relation, it only causes a small diminution of the same coefficient.
 If we imagine many of these shifts taking place while
ime goes on and, along with them, corresponding changes
'n the consumption coefficients — which is, after all, the normal
 path that technical progress takes — the input-output
:able is continuously upset and all functions change from one
moment to the next. On the other hand, the vertically integrated
 relations remain unaffected. The only consequence for
‘hem is that their coefficients gradually diminish through time
in a movement which, for analytical purposes, has been aporoximated
 in the present model by a smooth trend developing
 at a certain rate of change.
Concluding and summarising, we may say that, at any
ziven point of time, there exists between the static inputoutput
 model and the model presented in the previous pages
a very definite relation through a fully specifiable matrix of
coefficients. Considered at a given point of time, the inputoutput
 model is more analytical — it has much more to say
about the structure of an economic system. However, as time
goes on, and the conditions of production and of consumption
change (owing to technical progress, economies and diseconomies
 of scale, etc.) the inter-industry relations break down
and become different from one moment to the next, so that
a particular input-output table is needed for each stage in
the evolution of the economy under consideration. These

10] Pasinetti - pag. 105