The correct sequence of the market structure from most to least competitive is perfect competition, imperfect competition, oligopoly, and pure monopoly.
These results, by themselves inconsistent with the oligopoly-oligopsony hypothesis, may be due to the prevalence of other factors, such as efficiency wages.
Conjectural oligopoly models, in any event, have been more useful than game-theoretic oligopoly models in guiding the specification of empirical research in industrial economics.