182 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
Thus, the average relative deviation is respectively 5% and 89%, 
for y and ©, and for the United States only and 4% and 3% for 
the United States, Great Britain and France in 1913. In fact, in 
‘he first case, the range of @, is slightly greater than the range of Y 
for the first table. This order is reversed for the figures of the 
second table. 
I repeat that in my opinion we cannot attach any importance to 
the decimals. Perhaps some years from now it will be possible to 
have exact figures for the decimals but my conviction is that this is 
impossible at the moment. And so far as the figures for the United 
States are concerned, I must stress that there is some bias associated 
with the estimate of the rate of interest. It is very difficult indeed 
to estimate the pure rate of interest i. For example, after the war, 
American monetary policy was such that the rate of interest was 
maintained at artificially low levels and in this way the rate of 
interest did not reach the value which it would have had it there 
had been free play of the market mechanism. This explains the 
slight tendency mentioned bv FISHER. 
3. But that is not the real point. The real point is that the 
results which are found show a striking agreement as far as orders 
of magnitude are concerned; and at all events these results must 
be explained. The proposed theory can predict small variations of 
®, and y and in fact we verify that the estimates do not vary very 
much. 
4. My fourth point is the following. I am completely aware 
that it is impossible for me to say that this model is the only one 
which can explain the facts, because the empirical data we have are 
insufficient for any final and definite conclusion to be derived. 
I say only that the course of events is what it would be if this theory 
were correct, and no more than this. This theory and the model 
which illustrates it are compatible with all the known facts. 
I don’t say that this theory will continue to hold. Nobody 
knows this. I simply suggest that this theory can explain the fea- 
11] Allais - pag. 286