SEMAINE D'ÉTUDE SUR LE ROLE DE L’ANALYSE ECONOMETRIOUE ETC. 
cation and training become a necessary part of an economic 
model, not something which can be left on one side as a social 
process irrelevant to economics. 
Another important point to keep in mind about the rela- 
tionships in an economic model is whether they are to be used 
lo answer questions or to ask them. For example, if the model- 
builder knew enough about the alternative techniques of pro- 
duction that will become available in the near future in dif- 
ferent industries, he could say what changes in labour pro- 
ductivity could and should be brought about in order to reach 
certain objectives. In practice, however, the model-builder 
is most unlikely, at first, to know as much as this. But he can 
work out on reasonable assumptions a set of changes in labour 
productivity in different industries which would enable a given 
vector of output to be produced with a given quantity of labour. 
Then, instead of answering the question ‘what increase in 
labour productivity is needed in each industry’ he could ask 
the question ‘could the increase in labour productivity I have 
worked out be achieved and, if not, what are the obstacles to 
achieving it’. By bringing such questions out into the open and 
showing what is needed if certain results are to be obtained, 
a great deal can be learnt and the people responsible for action 
can be provided with useful information. It may be that an 
industry simply cannot do what a model initially suggests; but 
it may equally happen that it could do as much or more if it 
believed in other results of the model, for example the estim- 
ated future demand for its products. In this case the model- 
builder is simply providing agenda for industry discussions. 
This may often be more useful than trying to anticipate the 
outcome of these discussions, since the discussions themselves 
may provide information to the model-builder more reliable 
han he could possibly have reached on his own, and may thus 
enable him to produce statements about the possible future of 
the economy which are realistic as well as consistent. 
The final point I want to make about relationships con 
“11 Stone - pag. 11