Some Important Measures of Population Change

Rate of Natural Increase (RNI)

If the population is increased due to the difference of birth rate and death rate, it is called rate of natural increase (RNI). In other words, it is the difference between crude birth rate and crude death rate.

If the birth exceeds the death (+ve RNI), the population increases and vice versa. Similarly, if the birth equals to the death, then population becomes stable (or zero rate of natural increase).

Population Growth Rate

The population of a country changes continuously. Birth, death and migration are the demographic elements behind the population change. Population growth rate shows either the population of a country increasing or decreasing. Population growth is the sum of RNI and net migration, it is expressed in percent.

Sex Ratio

Sex ratio is the ratio of males to females in a given population and usually expressed as the number of males per 100 females. It is used for expressing sex composition of thepopulation.

Dependency Ratio

The dependency ratio is measured by considering the distribution of the population by three broad groups such as 0-14, 15-59, and 60 and above. In these age groups, the age group of 0-14 and 60 above are not productive and may not be able to earn their livelihood so they should depend upon the age groups of 15-59 years. Dependency ratio shows the number of persons dependent upon every 100 people of independent groups.

Population Doubling Time

Population Doubling Time is the estimated time taken to double the population. The doubling time is calculated by a simple mathematical calculation. Accordingly, if a number is increased by 1 percent, in approximately 70 years, it will be doubled. If a population is growing at 1 percent per year, it takes about 70 years to double.