To John C. Medaille,
      The similarity is that there is less concern with modeling the 
behavior of individual agents,
as these are assumed to be heterogeneous anyway.  Hence one is modeling over 
statistical
distributions, which in turn are often derived from models in statistical 
mechanics, where one
considers the aggregate behavior of particles as a statistical outcome 
rather than the individual
behavior of individual particles.

Barkley Rosser