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PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - ;

of this they find themselves forced to replace the essentially symbolic
concept of traditional economic theory by concrete operational concepts
 referring to directly observable and measurable facts with which
a business man, an engineer or a practical economic planner has to
reckon in the couse of his every day activities.
In some instances we find ourselves seeking collaboration with
other disciplines. In describing and analysing processes of production,
 an economic model builder must be prepared to speak the
language of a production manager and of an engineer; in dealing
with the structure and behavior of households, he must be prepared
to speak the language and use the concepts of a demographer and
a social-psychologist.
The time when the economist or the econometrician could limit his
efforts to construction of mathematical models — or devising more
sophisticated methods of statistical inference — is passing fast. He
has to take increasingly active part, not only in the actual use of these
models and application of these methods, but in the organization and
the direction of the fact gathering activities without which all theory
and methodology will continue to be no more than intellectual
exercise.

VIAHALANOBIS

There is one point in Professor WoLD’s observation about which
[ am not clear. When he said « forecasting » did he include
i targets »? It is possible to take suitable action to attain certain
targets which are considered desirable; this is the system, for example,
 in central planning in U.S.S.R. It is not forecasting based essentially
 on historical experience or time-series analysis but setting up
certain targets which it is desired to achieve over a certain period of
time. Would Professor WoLp include setting up of such targets
within forecasting?

1] Stone - pag. 96