348 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28 
instead of the observed values u= 0.32 and 1 - A=0.go0 respec- 
Hvely. 
Here again, if the exponential model is assumed to be 
correct, the divergences are the result of the incorrectness of 
hypothesis (H), but the concordance of orders of magnitude 
shows that the interpretation of reality corresponding to hypo- 
‘hesis (H) is acceptable as a first approximation. 
As might have been expected, the values of 0°=3.59 which 
nas been derived is of the same order of magnitude as the 
average production period, 0 =4.23. In point of fact, if the 
supplementary hypothesis (H’) that all investments involve 
a production period equal in length to the average production 
period is made in addition to hypothesis (H), it follows neces- 
sarily that 
y =6=4.23 
It may be concluded from this that if the formulation of 
the exponential model can be considered as conforming with 
reality, approximate assessment of the real situation can be 
made by considering the hypotheses (H) and (H’) as valid. 
Taking 0,=3.59, and using for illustrative purposes the 
value of 8; =0.25 (3 months) the following table can be derived. 
111 Allais - pag. 152