Another Tale of Two Tails: On Characterizations of Comparative Risk

We characterize the classes of utility functions that are consistent with different notions of mean preserving spreads introduced in the literature. This gives rise to a unified approach and extension of some definitions of increasing risk, including the concepts of Rothschild and Stiglitz (1970) and Landsberger and Meilijson (1990a,b). The main idea is to restrict the centers of the mean preserving spreads to an arbitrary subset.