458 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA
,
into the equational system we have to use in development planning.
We have for instance investment project specifications. We will
have tens of thousands of such projects. Each of them will be
described in engineering terms; for instance the sequence in
time in which certain input elements are to be made: labour,
products from domestic sectors, imports, etc., the burden which
this entails on the balance of payment is extremely important,
and so on. In most cases these data can be derived fairly correctly
from an engineering analysis. There may, of course, be some un-
certainties and you may — according to the price situation — shift
a little in the use of input elements, but let us disregard that point
for the moment. The engineering analysis will — with a fair degree
of approximation — give the essential information. Similarly with
regard to the time and the volume in which the capacity effect of
the investment emerges. If you are building a hydroelectric power
station, then you can say, from an engineering viewpoint that
«next year I'll have one machine coming along; the year after, I'll
have two more machines », and so on. All these things are given
from the engineering viewpoint with a fair degree of accuracy and
there is no question of trying to estimate the possible consequences
of adopting a section of these 1,000 or 10,000 projects by looking
back in our time series and discussing whether a certain time series
estimate will be « unbiased » or « immoral » or have some other
specific property which you are able to handle mathematically, but
which have little relevance for the actual problem of development
planning.
FISHER
The last point made in my reply to Professor WoLD is of course
in agreement with part of Professor FrRisCH’s remarks. There is a
growing literature on Bayesian estimation in which the decision
problem to be answered by the model determines the estimation
technique. This is a highly interesting development and it is one
with which I am in nearly complete sympathy. There are several
[6] Fisher - pag. 74
