  Extropy was introduced as a dual complement of the Shannon entropy. In this
investigation, we consider failure extropy and its dynamic version. Various
basic properties of these measures are presented. It is shown that the dynamic
failure extropy characterizes the distribution function uniquely. We also
consider weighted versions of these measures. Several virtues of the weighted
measures are explored. Finally, nonparametric estimators are introduced based
on the empirical distribution function.
