Simplified birth rate estimates under nonstable conditions.

Coale's robust birth rate estimate, obtained by adjusting the birth rate of a stable population selected by matching the observed population of both sexes under the age of 15, C(15), and the probability of survival of births to age 5, l5, is shown to be equal to the birth rate obtainable by reverse surviving the proportion under the age of 15. Variations of matching the criterion of Coale's method to the rate of increase and C(15) or l5 are shown to lead to variants of Coale's birth rate estimate that are also nearly equal to the reverse survival birth rate based on C(15). A simplified birth rate estimate that does not require reference to models of life tables or stable populations is suggested and some of its applications are illustrated.