Before revision:  Finally, a novel method of calculating  lifespan differential of a population from mortality indicators of its subpopulations is introduced and applied to the analysis of  lifespan differential in Israel from 1990 to 2000.
After revision:  Finally, a novel method of calculating the observed lifespan differential of a population from mortality indicators of its subpopulations is introduced and applied to the analysis of lifespan differential in Israel from 1990 to 2000.