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and which therefore have to be more complicated, at the moment 
we can’t do much better than stumble along as we are doing. 
\[AHALANOBIS 
[ should agree entirely. A model may be, should be indeed, as 
complicated as is necessary for an explanatory model or a decision 
model or to serve some other purpose. I am in complete sympathy 
with the study of such models. Even when adequate statistical 
data or other types of information are not available, working with 
such models in an imaginative way may lead to the collection of 
relevant data; this itself is a very useful task. Or, such studies 
may lead to advances in theory as often happens in physics. I have 
‘herefore nothing against using complicated models in any way. 
The questions which I raised had some ambiguity, and I think 
Dr. KooPMANS’ observation were justified. One object was that 
sometimes simple models are quite adequa? 
DORFMAN 
Yesterday we had a long discussion of the types of economic 
model, which left me very uncomfortable. We then seemed to 
conclude that there were three types of model, explanatory models, 
forecasting models, and decision models, in Professor FrIscH’s ter- 
minology. But I went away feeling that we had forgotten about 
some other kinds, and today we have had three examples of models 
that cannot be used for explaining any empirical observations, or 
forecasting the future, or making practical decisions. Today's 
models are intended to illuminate the logical consequences of some 
assumptions or conditions. We might call them a fourth type, logical 
or hypothetical models. I suspect that there are many other types 
sf model alsa 
Morishima - pag. =.