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PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
MAHALANOBIS 
I shall not speak on many of the detailed aspects of this 
particular model, because I am not competent to do so. The treat- 
ment of an important question by a very simplified model, I believe, 
throws some light on policy decisions. 
Also, I should like to raise one question, not with reference to 
the particular model just now discussed, but of a broader nature, 
which is of importance to an underdeveloped country like India, 
as distinguished from Japan and advanced countries, regarding the 
usefulness of complicated models generally. 1 should like briefly 
to mention our experience that when some complicated models are 
used, the question of unreliability of data becomes of crucial im- 
portance; Dr. JoHNSON has drawn attention to this point in his 
paper, and Professor LEONTIEF has also referred to it earlier. In 
another intervention I tried to indicate two gaps between the world 
of reality and the model. Firstly, the gap arising from the lack of 
availability or the lack of reliability of data; and secondly, another 
gap between the data and the model. These are questions, of course, 
of a very general nature, which however deserve serious attention 
of econometricians. 
KooPMANS 
I appreciate the support of Prof. MAHALANOBIS for what I tried 
to say earlier. At the same time I do not go as far as he does if I 
understand what he said to mean that there is something wrong in 
complicated-ness itself. I think we are entitled to make our models 
as complicated as we can manage as long as by that extra complica- 
tion we obtain added insight, and the extra complications do not 
prohibit communication of the findings. We are working at the 
frontier of our collective understanding of these problems, and while 
altimately we hope to end up with models that reflect reality better 
9] Morishima - pag. 36