Another important source of secondary variation has been identified
by Stanislaw Andrzejewski in his important but neglected book, Military
Organization and Society. As he has shown, both deductive logic and
empirical data indicate that the degree of inequality in societies of a
given level of technological development tends to vary inversely with what
he calls "the military participation ratio," that is the proportion of
the adult male population utilized in military operations (1966, p.49).