dependency ratio

dependency ratio A simple indicator of the age composition of the population which typically varies in the range 0.5 to 1.00. Early definitions of the dependency ratio refer to the total number of young dependants divided by the total number of persons of productive age. More recently, due to the economic burden of ageing populations, the dependency ratio is defined as the total number of young and old dependants divided by the population of working age—for example persons aged under 15 and 65 and over divided by persons aged 15–64, or persons aged under 20 and 60 and over divided by persons aged 20–59 years. In both definitions, the two parts of the population are identified purely by age, rather than with reference to numbers actually working and not working. As national data sources improve in quality and frequency, this third—more precise—definition becomes a possibility, and is used in some studies. The dependency ratio is used by demographers to monitor trends over time in the age structure and relate them to the fertility rate, the mortality rate, and other demographic, social, and economic indicators.