1. Department of Mathematics , Southern Illinois University , Carbondale, IL 62901;2. Department of Statistics , University of Illinois , 725 S. Wright Street, Champaign, IL 61820
Abstract:
Jacobson (1969) proved that the variance of a unimodal distribution on the unit interval is bounded above by 1/9. This paper generalizes Jacobson's result by deriving sharp upper bounds for the variances of α-unimodal distributions and for the variances of S-shaped distributions.