SEMAINE D'ÉTUDE SUR LE ROLE DE L’ANALYSE ECONOMETRIOUE FTC 
20] 
struction cost is not the only relevant cost figure (even if 
discounted); separate attention should be given to fiscal drains 
in individual years. As a final instance, the impact of the 
financing of a project on the private sector gives rise to a similar 
distinction. To the extent that the financing induces retrench- 
ment in consumption expenditures there is one kind of cost (one 
might even want to distinguish among the socio-economic strata 
which retrench). To the extent that the financing induces a 
reduction in private investment, there is another kind of cost, 
especially if the social and private rates of interest diverge. 
The two cannot be added meaningfully dollar for dollar, nor 
Is it easy to assign an exchange rate between them a priori. 
In short then, what I as an econometrician contemplate is 
that the assessment of a public investment be based on a model 
of that investment that recognizes its consequences in many 
dimensions and that exhibits the full range of choice and substi- 
tutability among these dimensions. Final adoption or rejection 
of a project can be decided only when the best design it is 
feasible to produce is at hand, one that takes account of al! 
the significant dimensions. 
This approach requires a new kind of cooperation among 
engineers, economists, fiscal analysts, and senior policy of- 
ficials. The engineer is not asked to submit a design as a kind 
of fait accompli to be analyzed and perhaps accepted by the 
other officials. He is rather made more integral to the ap. 
praisal and decision process. He is to collaborate in the formu- 
lation of the model of the investment and to present estimates 
of the requisite functions, where possible. Where that is 
not possible, a frequent situation, the engineer will have to 
contribute and analyze some more detailed technological rela- 
tionships that I shall discuss more fully below. The economist 
contributes his guesses of plausible targets and estimates of 
money value for those outputs for which monetary values are 
appropriate. All contribute to the construction, the testing, 
the appraisal, and the revision of the model of the contemplated 
ov Dorfman - pag. 1+