Demographic Concepts and Terms_Elements of Population by Imran Ahmad Sajid-06-Dec-2010

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Demographic Concepts andTerms/Elements of Population

By: Imran Ahmad Sajid

Presentation at Department of Social Work, University of Peshawar, on Monday,

06-Dec-2010

Emergence of DemographyPeople are the material out of which nations and societies are made, and

concern over the number of people runs through history, 1from the ancient times

of Pharaoh, Greece, and Rome to the medieval and modern era. King William,

Duke of Normandy, ordered a census of England after its conquest in 1066 whichresulted in Doomsday Book. Pharaohs of Egypt began doing census as early as

2500 BC. The emperors of Rome also counted and assessed their subjects

frequentlyAugustus ordered a count of the entire empire for three times during

his period. Why all this interest in counting people? To estimate tax revenue and

military manpower. 2

To know how much revenue a tax can produce, a government needs to know

how many people will be paying it. Moreover, only by knowing how many people

live in a particular district can the central government be sure that local officials

are not embezzling. For example, a local tax official might report to the imperialgovernment that there are 5,000 tax paying families in his district when there

are, in fact, 8,000, thus enabling him to pocket the taxes paid by 3,000 families.

By the same token, only by knowing the number of able-bodied males of military

age can a ruler estimate how large an army he can raise.

Thus, from ancient times, governments constituted census. However, there was

a problem with all these censuses, with the passage of time, they become out-

dated. The reason was obvious; populations often change rapidly. Therefore, it

may be necessary to redo a census frequently to have accurate information.

However, censuses are very expensive; therefore governments are oftenreluctant to conduct them. But over time, ways have been found to gauge

population changes. It is because of the fact that populations often fluctuate in

size; governments encouraged inquiry into why this occurs. Thus was born the

science ofdemography.3

The word demography is formed from the Greek word demos, meaning people

and graphymeaning description. Doing demography means describing people.

1 Hustcinson. (1967). The Population Debate. Boston: Houghton Mifflin Company. P. 1.2

Rodney Stark. (1989). Sociology. [3rd

Ed.]. Belmont, California: Wadsworth PublishingCompany. P. 520.3 Ibid. p. 522.


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Whenever you here about population growth, death rate, birth rate, fertility rate

etc, you are hearing to the work done by the demographers.

Demography is defined as, the scientific study of human population primarily

with respect to their size, structure and development (change)----UN

It seems that demography is interested in number of people, but it is more than

just a numbers game. It poses crucial questions about the effects of population

growth and how it may be controlled or diverted.

Demographic Concepts and Terms/Elements of

PopulationAs we know, populations grow or decline due to the changes in fertility, mortality

or migrations patterns. For a scientific demographic analysis understanding of

several basic concepts (elements of) population is essential. These including;

Fertility

o Fecundity

o Crude birth rate

o Total Fertility rate

Mortality

o Crude death rate

o Infant mortality rate

o Life expectancy

Migration

o Immigration

o Emigration

Population growth

o Positive population growth

o Negative population growth

o Zero population growth


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A- FertilityAny study of human population must concern itself with how many people are

born.4 Fertility occupies the central position in demographic analysis. The growth

of population depends on fertility.

Fertilityis the actual number of births in a given population.5 On the other hand,fertilityrate is the annual number of births per 1,000 women of childbearing age,

usually between 15-44.

Fertility is different from fecunditywhich is thephysiological ability to have

children. Most women during child bearing age (15-45) are capable of producing

children. During this time, a woman could potentially have up to 25-30 children;

however, this number is far from real life. It is for the reason that there are some

barriers to child bearing including health, culture, social norms, financial

concerns, and personal choice etc.

Fertility is of two types, natural fertility and controlled fertility. Natural fertility is

the fertility which exists in the absence of deliberate birth control. Controlled

fertility is the fertility which involves a deliberate use of birth control. 6

i. Crude Birth RateFertility is often measured through Crude Birth Rate (let it be denoted by b). It

is the number of annual live births per 1,000 people in a given population.7 Live

births mean it does not include still births (born dead). A live birth is defined by

WHO as, any born human being who demonstrates independent signs of life,

including breathing, voluntary muscle movement, or heartbeat. CBR is

calculated by the following formula;

Total number of live births in a year x 1,000

Total mid year population

Consider the following hypothetical example;

Total population = 30,000

Live births per year = 150

By putting the values in formula, we have;

Birth Rate = 150 x 1000 = 50

3000

4 John J. Macionis. (1993). Sociology. [4th Ed.]. New Jersey: A Simon and SchusterCompany. P. 588.5 Henry L. Tischler. (1998). Introduction to Sociology. [8th Ed.]. Balmont, California:Wadsworth Publishing Company. P. 416.6

Anwar Alam. (2008). Demography: Population Explosion and Control. Peshawar:Department of Sociology, University of Peshawar. P. 105.7 Ibid.


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There were about 40,94000 live births in Pakistan during 2008 in a population of

163.76 million.8 By our formula we have

CBR = 40,94000 x 1000 = 25

163,760,000

A CBR of 30 and above is considered to be high while below 20 is considered to

be low. This birth rate is termed crude because it is based on the entire

population irrespective gender, race, territorial distribution, origin etc.

B- MortalityMortality is the percentage of deaths in a population. Death, as defined by the

UN, is the permanent disappearance of all evidence of life at any time after birth

has taken place.

i. Crude Death RateCorresponding to the Crude Birth Rate, demographers use a Crude Death Rate.

CDR (let it be denoted by d)is the annual numbers of deaths per 1,000 people

in a given population.9 CDR is calculated by the following formula;

Total number of Deaths in a year x 1,000

Total mid year population


Total population = 3,000

deaths per year = 75

By putting the values in formula, we have;

Death Rate = 75 x 1000 = 25

3000

There were about 12,60,952 deaths in Pakistan during 2008 in a population of163.76 million.10 By our formula we have;

CDR = 12.60,952 x 1000 = 7.7

163,760,000

CDR blow 10 is considered to be low while CDR above 20 are considered to be

very high.

8 Ministry of Finance. (2009). Economic Survey of Pakistan 2008-09. Islamabad: Ministryof Finance, Government of Pakistan.9

Henry L. Tischler. (1998). Op.Cit. p. 417.10 Ministry of Finance. (2009). Economic Survey of Pakistan 2008-09. Islamabad: Ministryof Finance, Government of Pakistan.


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ii. Infant Mortality RateA third widely used demographic measure is the infant mortality rate (IMR). It is

the number of children who die within the first year of life per 1,000 live births.

Out of 1,000 babies born this year in Pakistan, more than 70 will die till next

year. It means that out of 4094000 live births in Pakistan during 2008, more than

287000 died before 2009.

IMR offers a good general measure of overall quality of life, level of health

services and physical development in a society.

iii. Life ExpectancyLife expectancy or Life expectancy at birth is the average number of years that a

newborn baby can expect to live. Countries with high infant mortality rate have a

lower life expectancy while the countries with a lower level of IMR have a high

level of life expectancy. In Pakistan, life expectancy for both sexes is 65.2 years

(65.4/m and 65.7/f). Likewise, life expectancy in less developed countries (LDCs)is around 60 while in developed countries it is around 80s.

C- MigrationPopulations also change when people move into or outside a society. Migration is

the movement of people from one geographical area to another11.

Migration is sometimes involuntary, as illustrated by arrival of Afghan and Indian

refugees into Pakistan during 80s and 50s respectively. It is also voluntary whenpeople are motivated to move by complex push and pull factors.12

i. ImmigrationImmigration is the movement of people into a territory (let it be denoted by I).

In other words, it is the process of entering to another territory. For example,

migrants coming from Afghanistan into Pakistan are immigrants. They are

immigrating to Pakistan.

ii. Emigration

Emigration is the movement of people out of a territory (let it be denoted by e).For example, Pakistanis going to Malaysia or Australia for permanent residence

are emigrating from Pakistan. So, it is the process of leaving a country

permanently.

Immigration and emigration both moves simultaneously. People, at the same

time, are immigrants and emigrants simultaneously. Aslam leaving Pakistan is

emigrating from Pakistan and moving to Dubai for permanent residence is

immigrant to Dubai government.

11 Henry L. Tischler. (1998). Op.Cit. p. 418.12 Macionis. (1993). Op. Cit. p. 589.


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iii. Net MigrationIt is the difference between immigration and emigration. It is measure by

number of people entering into a population minus number of people leaving

that population. it is calculated through following formula;

Net-migration = immigrants emigrants x 1000

Total population


Immigrants = 50

Emigrants = 65

Total population = 3000

By putting the values in the formula we have;

Net-migration = 50-65 x 1000= -5

3000

D- Population GrowthPopulation growth is known as change in any population over time.13 The rate of

change in a population over a period of time is known as population growth rate

(let it be denoted by r). Population growth rate is calculated through thefollowing formula;

Births Deaths + Net-migration


Total population = 3000

Birth rate = 50

Death rate = 25

Net migration rate = -5

Population Growth Rate 50-25-5 x 1000 = 20 = 6.66

3000 3

13

Population Growth.

(2010). Wikipedia. In the website Wikipedia the FreeEncyclopedia. Retrieved on December 04, 2010 fromhttp://en.wikipedia.org/wiki/Population_growth
http://en.wikipedia.org/wiki/Population_growthhttp://en.wikipedia.org/wiki/Population_growth


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i. Positive Population GrowthPositive population growth is a situation in which the number of newborns and

the number of immigrants is greater than the number of dying and emigrating

people. Mathematically it can be expressed as

Positive population growth = b + i > d + e

Pakistan, India, Bangladesh and most of other developing countries are

experiencing a positive population growth. Growth rate in Pakistan was 1.8

percent for 2009.

ii. Negative Population GrowthPopulation growth will be termed as negative when births plus immigration is

less then deaths plus emigration. Mathematically it can be expressed as

Negative population growth = b + i < d + e

Japan, Germany, Italy (and most of other European countries), and Russia, are

experiencing a negative population growth rate.

iii. Zero Population GrowthZero population growth is a situation in which the number of new births and the

number of immigrants in a population is no more than the number of dying

people and the number of emigrants, so that the population size remains the

same for the period of time.

In other words, population is in equilibrium with a growth rate of zero, when

births plus immigrants is equal to deaths plus emigrants. Mathematically,

Zero population growth = b + i = d + e

Spain, Belgium, Austria, and Green land are experiencing almost zero population

growth rates.

Conclusion

Proper understanding of demographic concepts and terms/elements ofpopulation change are necessary for demographers similar to the knowledge of

accounting terminologies for an accountant.

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Demographic Concepts and Terms_Elements of Population by Imran Ahmad Sajid-06-Dec-2010