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Note on Some Important Measures of Population Change

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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.

  • If the population is increased due to the difference of birth rate and death rate, it is called rate of natural increase.
  • Population growth is the sum of RNI and net migration.
  • Sex ratio is the ratio of males to females in a given population and usually expressed as the number of males per 100 females.
  • Population Doubling Time is the estimated time taken to double the population.
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Very Short Questions

The difference between sex ratio and dependency ratio is given below:

Sex ratio Dependency ratio

The sex ratio, generally, denotes the number of males per 100 females.
The result which comes after dividing the population of 0-14 and 60 years and above by the population of 15-59 years age group and multiplied by 100 is called dependency ratio.

Sex ratio =Total number of males × 100 / Total number of females
Dependency ratio=Number of dependence × 100 / Active population

It is used to find out the ratio of male and female.
It is used to find out the ratio of active and dependent population.

Sex ratio increases due to preference to son. It increases due to increasing health status and facilities.

Difference between population size and population growth rate is given below:

Population size Population growth rate
Population size means the number of person s in population Population growth rate means the joint sum of natural growth rate of population and the net migration.
Population size is measured in number. Population growth rate is measured in percentage.

Here,
Midyear population (P) =4, 00,000
Birth (B) =25,000
Death (D) = 4,500
Immigration (I)=4000
Emigrants (E) =1098
According to the formula,
Net Migration rate(NMR) = ( (I-E) × 1000 ) / P
= ((4000-1098) × 1000) / 4,00,000
= (2092) / 400
= 7.25 Per thousand

Gross migration Rate(GMR) = ((I+E) × 1000 ) / P
= ((4000+1098) × 1000) / 4,00,000
= 5098 / 400
= 12.74
GMR =12.74 per thousand

Rate of Natural Increase:
= ((CBR-CDR) × 100) /1000
First of all let's calculate CBR & CDR
CBR = B × 1000 / P
= 25000 × 1000 / 4,00,000
=250 / 4
= 62.5

CDR= D × 100 / P
= 4500 × 1000 / 400000
= 45 / 4
= 11.25

CBR =62.5 per thousand CDR= 11.25 per thousand
Now,
We know that
RNI =((CBR-CDR) × 100) / 1000
=(62.5-11.25) × 100) / 1000
= -5.12 %
Rate of natural increase -5.12 %

Population Growth Rate
= (CBR-CDR+NMR) × 100 / 1000
= 58.5 / 10
= 5.85 %
Rate of population growth = 5.85 %

Population Doubling times
= 70 / Annual growth rate
=70 / 5.85
= 11.96
Population doubling time = 11.95 %

Given,
Crude Birth rate(CBR)= 20.5
Crude death rate(CDR)= 12.6
Net migration rate (NMR)= 8
Rate of natural increase (RNI)= ?
Population growth rate (PGR)= ?

We know,
RNI = (CBR-CDR)/1000*100
= (20.5-12.6)/1000*100
=. 79

Again PGR = (CBR-NMR)/1000 *100
=20.5-12.6+8/1000*100
=1.59%

Therefore, the RNI for the country's population is. 79% and PGR is 1.59% per annum.

0%
  • What is the full form of RNI?

    Root of Natural Increase
    Rate of Natural Incident
    Rate of Natural Increase
    Rate of National Increase
  • Rate of Natural Increase is ______.

    the difference between total fertility rate and infant mortality death rate
    the difference between crude birth rate and crude death rate
    the difference between crude birth rate and age specific death rate
    the difference between general fertility rate and crude death rate
  • The ratio of males to females in a given population and usually expressed as the number of males per 100 females is called ______.

    dependency ratio
    sex ratio
    age ratio
    accuracy ratio
  • If the birth equals to the death, then population becomes ______.

    high
    stable
    more
    less
  • Population growth is the ______.

    difference of RNI and net migration
    difference of RNI and crude birth
    sum of RNI and net migration
    sum of gross migration and net migration
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