7 
The stochastic models have often been criticised for 
their lack of economic content. Perhaps it has been 
overlooked that they only represent the first steps 
in a new exceedingly difficult terrain. It may be 
thought that the work of Champernowne, Yule, Simon, 
Wold-Whittle contains the seed of future studies which 
will reveal their full potentiality only when they 
are extended to distributions in several dimensions. 
Josef Steindl