Directional Monotone Comparative Statics

Abstract

Many questions of interest in economics can be stated in terms of monotone comparative statics: If a parameter of a constrained optimization problem increases, when does its solution increase as well. This paper characterizes monotone comparative statics in different directions in finite-dimensional Euclidean space. These new characterizations are ordinal and retain the same flavor as their counterparts in the standard theory, showing new connections to the standard theory. The results are highlighted by several applications in consumer theory, producer theory and game theory. These applications were previously outside the scope of the standard theory of monotone comparative statics.

Keywords: monotone comparative statics, directional single-crossing property, directional set order

JEL Classification: C61, C70, D00