Simon's result that decision makers only focus on "expected values" of stochastic variables was very sensitive to the assumed structure of the problem, hence indirectly on the formulation of expectations. This lack of a general theory of expectations was an unsatisfactory state of affairs and proved to be key in Muth's approach to solve the problem which has often been termed interaction between expectations and reality. In his article from 1961, Muth writes: "To make dynamic economic models complete, various expectational formulas have been used. There is, however, little evidence to suggest that the presumed relations bear a resemblance to the way the economy works."