SEMAINE D ETUDE SUR LE ROLE DE L’ANALYSE ECONOMETRIQUE ETC. 731 
where P’ is written for G.N.P., and A’ represents the amorti- 
sation relative to the range of durable goods for the economy 
as a whole, per unit of time (,. 
Further, from (1.6-5) wc have 
116-8) 
with 
(116-9) 
116-10) 
where I's and I'y denote gross and net investment respectively 
Under the existing convention of national accounting, cap- 
tal is for all practical purposes defined as goods whose life 
expectancy exceeds one year, and indeed in practise, as goods 
whose life expectancy is at least five years, the shortest period 
over which amortization is calculated. 
As a result of this convention, the lining of a Martin oven, 
which normally lasts a few months, is written off as an operat- 
‘ng expense, whereas the structure of the oven is considered 
1s an investment. 
With rules of this type, it is generally found that 
116-11) 
K Re 
n wich K is of the order of 0.1 to 0.z. 
(!) ALLAIS (1954), Les Fondements comptables de la macroéconomique 
The Accounting Basis of Macroeconomics). 
SH 
Allais - pag. 35