An evaluation of Brass mortality estimates under conditions of declining mortality.

An evaluation of the Brass childhood mortality estimates under conditions of declining mortality shows them to overestimate current mortality. Error increases as the rate of mortality decline increases, as the childhood age up to which cumulative mortality is being estimated increases, and as age at onset of childbearing decreases. We use the results to develop a method for correcting the Brass estimates for the effects of quasistability. The method requires an estimate of the rate of mortality decline within the population in addition to information on the pattern of childbearing in the population.