Changing vital rates and age distributions.

Abstract In a time of rapid change in birth and death rates demographers need to know the consequences of such changes for age distribution. Does the fall in death rates tend to make the age distribution older? It certainly enables individuals to grow older, but for population aggregates the effect depends on the ages at which mortality improves. Coale, Stolnitz, Schwarz, Lorimer, the United Nations and other writers have investigated trends in age-specific birth and death rates. In particular they have demonstrated that the falling mortality which is now nearly universal does not generally make the population older and sometimes makes it younger. The present article contributes a technique for further examination of this phenomenon.