SEMAINE D'ÉTUDE SUR LE ROLE DE L ANALYSE ECONOMETRIQUE ETC 
the exponential amortization which is a characteristic oi th 
exponential model (1). 
It is shown in the Appendix to the present study that under 
the very general hypothesis that the function [3(8)e*’ can be 
developed as a Taylor series, at least for a certain value of p, 
the coefficient A (which is equal to 1 in the exponential model) 
will not differ generally from unity by more than +o.5, for 
hypotheses which can reasonably be accepted. 
It follows from this that while the exponential model clearly 
may not offer a perfect portrayal of real conditions, it doubtless 
does not differ therefrom all that much, so that, at least in 
terms of a first approximation, it is capable of depicting the 
essential features of reality quite correctly. 
If this approximation is deemed insufficient, the develop 
ment of the function 3(6)e*’ as a Tavlor series of which the very 
first terms only are retained, provides as far as can be judged 
a reasonable representation of actual conditions (# 
The Value of the Model 
337. It follows from the preceding dimission that. 
a) the model is consistent with the information which ca.. 
obtained from available statistical data: 
b) it cannot be proved that the assumptions made are the only 
ones which would give results consistent with available data 
y From relation (z:zc 
x 
Thus if (0) declines more rapidly than 
© © we have 
since 
for (60)=e ©/v. 
(3) See Appendix 
.| Allais - pag. 179