1194 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - z2§ 
not a total analysis of the economic system. In the programme of 
the Study Week there are several other important contributions at 
an intermediate level between micro and macro analysis. Specific 
reference is made to reports that focus on methods and techniques 
of general scope; a typical case in point is the device of shadow 
prices dealt with by Professor DORFMAN. 
KoorMmANS 
I have a question to Prof. JoHNSON in response to his comment 
on investment in research. Research and development in industry 
is often exportable to underdeveloped countries. My question to him 
is whether this is also true in agriculture, or whether because of the 
specificity of climate, soil and varieties, agricultural research has to 
be essentially done over for each agricultural area. 
LEONTIEF 
Professor JOHNSON’s penetrating observations on the role which 
econometric models might play in advancing the growth of under- 
developed areas and possibly even of developed countries naturally 
lead to the question of choice between special and general purpose 
models. Throughout our present discussion much stress was put on 
the necessity of building special models for special purposes on the 
one hand, and on the other hand it was emphasized that the same 
model can serve several different purposes. 
Most of the difficult economic problems are those which involve 
discovery and tracing through unsuspected secondary relationships 
between the different parts of the economic system. A policy maker, 
as a rule, is able to assess correctly — even without any help from the 
econometrician — the obvious direct effect of measures which he is 
about to recommend. Quite often he does neglect or disregard, ho- 
wever, the indirect effects which might be unimportant from the point 
‘161 Johnson - pag. 54