 In the course of analysis, "comparative statics", changes in equilibrium of the system that result from a parameter change of the system, is formalized and most clearly stated (Kehoe, 1987, p. 517).The "correspondence principle" is that the "stability" of equilibrium for a system (such as a market or economy) implies meaningful theorems in comparative statics.Alternatively, the hypothesis of stability imposes directional restrictions on the movement of the system (Samuelson, pp.