One of the principal problems of demography is that of comparing the mortality and fertility of different populations or of one population at different periods of time. This note defines and discusses briefly some of the measures which have been used for this purpose.
Notation
aPx number of persons in age group x in the population being considered (the ‘actual’ population).
amx death-rate in age group x in the actual population.
sPx,8mx the corresponding number of persons and death-rate in a population chosen as standard (the ‘standard’ population).
aM crude death-rate in the actual population.
sM crude death-rate in the standard population.
tx number of ages included in age group x.
The standard population may, and in fact usually will, be an actual population in the sense that it is a population which existed at some particular time.