1. Concepts of Demography By Dr Arshad Usmani Lahore, Pakistan

2. DEMOGRAPHY It focuses on 3 phenomena: Changes in population size
Demography is scientific study of human population
It focuses on 3 phenomena:
Changes in population size
Composition of population
Population distribution in space
Important ‘demographic processes’ include: fertility, mortality, marriage, education & social mobility

3. Sources of Demographic Statistics:
In a broader sense, additional characteristics such as ethnicity (race, mother tongue), social characteristics (marital status, literacy, educational attainment, women’s status), and economic characteristics (employment status, occupation, income) also need to be considered when describing population characteristics
Census
National Survey
Registration of vital events
Demographic Studies
Sources of Demographic Statistics:

4. Definition of Key Words
Population Studies
Population studies are concerned not only with population variables but also with relationships between population changes & other variables – social, economic, political, biological, genetic, geographical, environmental, health & the like
Definition of Key Words
Size refers to the number persons in the population
Distribution refers to the arrangement of the population in space at a given time
Structure is the distribution of population among its sex & age groupings

5. Key Words
Change is the growth or decline of the total population or one of its structural units. The components of change total population are births, deaths, & migrations
Age-Sex Composition of a population refers to the proportion of males & females in different age-groups. It has a direct bearing on social, economic, health needs of communities or countries. In an “old” population, for example, the society has to arrange for the care of the elderly, & the country’s health system must be organized accordingly. In a “young” population, on the other hand, the country has to provide more schools, immunizations, & economic support for the young
Net-Migration refers to the total number of persons added or subtracted from a population as a result of the combined effect of immigration & emigration

6. Key Words
Urbanization refers to mass migration of rural population into urban centers resulting in increasing the urban population & growth of cities
Population Growth Rate (%/ year) is the rate at which a given population is expected to increase in a given period of time.
Population Doubling Time refers to the time that would take for a population to double. Because the population increase is on the compound interest formula, a 1% per year increase would cause the population to double in about 70 years. If the population is increasing at 3% per year, than the doubling time will be 23.3 years

7. Key Words
Population Pyramid is a pictorial presentation of the age-sex composition of a population
Replacement Level Fertility (or Zero population growth) is activated when a couple has two births during their reproductive life, just enough to replace themselves. At a community scale, the replacement level is considered when there are, on the average, 2.1 births per woman, to compensate for child deaths
Momentum of Population Growth is the characteristic of population growth when a sharp decline in births does not bring in an immediate reduction in natural increase

8. Population Dynamics
There are four ways in which the number of people in an area can change during two time periods t0 & t1
Pt1 = Pto + (B – D) + (IM – OM)
B = number of live births to mothers in the area
D = number of residents died
IM = number of persons moving into the area fro permanent residence
OM = number of persons moving out of the area to live elsewhere
Thus the population of an area may change due to natural reasons (B – D) known as natural increase or due to migration (IM – OM) known as net-migration. Subsequently:
Population Growth = Natural Increase Net Migration

9. Population Composition
While characteristic is an attribute of an individual (e.g. male, young, healthy, employed etc), composition is a property of a group of people. It describes how the total given population is constituted (e.g. 51% males, 20% below age 5, 85% healthy 7& 30% employed etc).
Dependency Ratio is an index summarizing an age distribution. Strictly, this is he ratio of population who are economically not active to those who are economically active. However, due to the difficulties in defining economic activity in many countries, especially when international comparisons are made, a ratio of age group is used instead:

10. Dependency Ratio Population Composition (Cont’d)
= Children + Elderly X 100
Working Age
= Pop below & above X 100
Pop 15 – 64 years
Dependency Ratio of Pakistan = 95.1
Dependency Ratio of UK = 66.5
Sex Ratio: The overall sex ratio is simply the ratio of males to females in the population & is calculated by taking the number of males in a population & dividing it by the number of females in the same population
Sex Ratio = Number of Males X 100
Number of Females

11. Demographic Cycle
World history suggests that every nation passes through a demographic cycle. The stages are:
High Stationary Stage: characterized by high birth rate and high death rate
Early Expanding: The death rate begins to decline while birth rate remains unchanged
Late Expanding: The death rate declined still further and birth rate tend to fall
Low Stationary Stage: Low birth and low death rates
Declining Stage: birth rate is lower than the death rate and population starts declining

12. Demographic Transition
Old Balance: (High fertility & High Mortality)
A large supply of births was necessary to compensate for the large number of deaths. MMR & IMR extremely high
New Balance: (Low fertility & Low Mortality)
Represents an improved condition of human efficiency & health, with fewer deaths considerably less efforts required to bring a generation to maturity. Production of agricultural & industrial commodities is greater & life style is more comfortable
Imbalance: (High Fertility & Low Mortality)
In between old & new balance is the period of rapid natural increase. This growth is helpful for under-populated nations. Too fast growth of population leading economic, social & political chaos ( being faced by numerous developing countries including Pakistan)

13. Phases of Demographic Transition
Birth Rates
Death Rates
Natural Increase
Example
Europe prior to 15th century, most other developing countries till the 19th century
High
High
Zero to very slow
High
Declining
Slow
Europe 17th century, India 1930s – 40s
High
Low
Rapid
Europe 18th century, Pakistan 1970s
Declining
Low
Slow
Europe 19th century, East Asian countries in the mid 20th century
Low
Low
Zero or very slow
Europe, Japan & USA

14. World PopulationTrend/ Population Dynamics:
2000 years ago
250 million population
1800
978 million
1900
1650 million
1950
2.5 billion
1970
3.6 billion
1980
4.4 billion
1985
4.8 billion
2000
6 billion

15. POPULATION EXPLOSION
The rampant population growth is viewed as the greatest obstacle to the economic & social development of the majority of peoples in the underdeveloped world
Approximately 95% of population growth is in developing countries
Currently, 1/3 of the world population is < 15, & will soon enter the reproductive bracket, giving more potential for population growth
The expected number of births per woman, at current fertility rate is:
Africa
Asia
Latin America 3.4
North America 2.0
Europe 1.6

16. Implications of Population Explosion
Economic implications
Due to population explosion there are
Short term pressure affects during 2-3 decade
Long term over next century and beyond economic affects
Demographic Implications
In population with low birth and death rate, 20-30% of population is under 15; 9-13% is 65 or more. The median age for this population is 32 and there is increased demand for senior citizen

17. Implications of Population Explosion
Environmental / Ecological Implications
Due to population explosion there are
Short term pressure affects during 2-3 decade
Long term over next century and beyond economic affects
Social / Political Implications
In population with low birth and death rate, 20-30% of population is under 15; 9-13% is 65 or more. The median age for this population is 32 and there is increased demand for senior citizens

18. Age Sex Ratio for Selected Age Groups
U.K.
Pakistan
0 – 4
105
10 – 14
103
109
45 – 49
101
127
60 – 64 89
134
70 – 74 73
209
75 + 37
173
All ages 95
108

19. Percent of Population by Age
Pakistan
U.K.
0 -14
44.5
22.2
15 – 64
51.2
60.0
65 & above
4.2
17.8