Mortality of a heterogeneous cohort; description and implications

"A recent model for heterogeneous mortality by Vaupel et al....is shown to be based on incorrect definitions. An alternative formulation is presented. The results indicate that current methods for computing the survivorship and life expectation functions underestimate the true values. A method is given for determining the possible magnitude of this underestimation. The method is illustrated by a numerical example using U.S. data."