SEMAINE D'ÉTUDE SUR LE ROLE DE L'ANALYSE ECONOMETRIQUE ETC. 
Te 
places in my paper in which this appears rather close to the surface. 
In general, I have said that the choice is between « consistency > 
and « efficiency » and I usually take the direction of opting for con- 
sistency. However, I tried to point out in the paper that this choice 
rather depends on what one expects to do with the results after one 
has obtained them. On the other hand, detailed analysis of the 
dependency of estimators in economy-wide econometric models on 
the use that is to be made of the results is difficult and so far only 
in its infancy. It does seem likely that properties of estimators 
such as consistency, unbiasedness, efficiency, and so forth, are pro- 
perties which one believes are likely to be relevant in a rather wide 
class of decision problems. 
Now for that part of Professor FRISCH’s comments which deals 
with the use of persuasive definitions. While I am not out of sym- 
pathy with the argument that use of such terms as « unbiased », 
« consistency », and « instrument », may be misleading in that such 
words carry connotations from general application, I must say that 
I think Professor FRISCH’s remarks on this point are irrelevant as 
regards my paper. However unfortunate the use of such terms may 
be, there is a long and distinguished history of their use in this way 
and while it may be too bad that such usage has come about, if 
is rather late for me to do anything about it. 
I must, however, comment specifically on Professor FRISCH's 
discussion of my use of the word « instrument » since I am unable 
to tell whether he actually misunderstands me or whether this is 
just another example of the unfortunate use of a word with several 
connotations.  « Instrument » in the theory of economic policy, 
where we owe much to Professor FRISCH, means a variable which 
can be controlled by a policy maker and which can be used to move 
toward those goals which the policy maker finds desirable. « In 
strument » as I have used it is short for « instrumental variable » 
as the context of my paper makes abundantly clear. In this sense, 
it means a variable which can be taken to be uncorrelated with 
the disturbances but whose movements influence the endogenous 
variables of the system. Such a variable is used as an instrument 
(6] Fisher - pag. 7°