A note on Onicescu's informational energy and correlation coefficient in exponential families

Abstract

The informational energy of Onicescu is a positive quantity that measures the amount of uncertainty of a random variable. But contrary to Shannon's entropy, the informational energy increases when randomness decreases. We report closed-form formula for Onicescu's informational energy and its associated correlation coefficient when the probability distributions belong to an exponential family. We show how to instantiate the generic formula for several common exponential families.