324 PONTIFICIAE ACADEMIAE SCIENTIARVM SCRIPTA VARIA - 28

The exponential model thus leads to the expectation that
the value of the capital-output ratio will differ little across countries
 at different times.
If we use COLIN CLARK’s figures, consisting of 58 estimates
for 21 countries for different dates between 1805 and 1953,
we find that they are lognormally distributed with a median
value of 3.54 (1).
The overall results are therefore as follows:

U.S.A., 1880-1956 (median of 12 observations) . . 3.46
U.S.A., France, U.K., 1913 (average) . . . . 3.72
World - 1805-1953 (median of 58 observations) . . 3.54

The concordance of these different estimates is absolutely
remarkable. It suggests a temporal and spatial regularity
which in any case must be explained.
The explanation given by the model is a simple one.

c) Constancy of the Ratio C/R,

325. The exponential model contains a very remarkable relationship:


325-1)

C()=©, Rolf)

2
|" }

According to this expression, statistical analysis should show
an approximative stability over space and in time of the ratio
of capital to primarv income.

() Arrars (1960 A), pp. 54-57; (1062 A), p. 72:
(?) Relation (251-9). PP. 54-57; (1962 A), p. 743

11] Allais - pag. 128