Concepts of Demography By Dr Arshad Usmani Lahore, Pakistan

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Concepts of DemographyBy Dr Arshad
UsmaniLahore, Pakistan
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DEMOGRAPHY

• 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

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• In a broader sense, additional characteristics
  such as ethnicity (race, mother tongue), social
  characteristics (marital status, literacy,
  educational attainment, womens 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
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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

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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 countrys 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

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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

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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

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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

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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

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• Population Composition (Contd)
• Dependency Ratio
• Children Elderly X 100
• Working Age
• Pop below 15 65 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

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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

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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)

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Phases of Demographic Transition
Example
Natural Increase
Death Rates
Birth Rates
Europe prior to 15th century, most other
developing countries till the 19th century
Zero to very slow
High
High
Europe 17th century, India 1930s 40s
Slow
Declining
High
Europe 18th century, Pakistan 1970s
Rapid
Low
High
Europe 19th century, East Asian countries in the
mid 20th century
Slow
Low
Declining
Europe, Japan USA
Zero or very slow
Low
Low
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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
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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 lt 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 6.1
• Asia 3.2
• Latin America 3.4
• North America 2.0
• Europe 1.6

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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

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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

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Age Sex Ratio for Selected Age Groups
Age Group U.K. Pakistan
0 4 105 105
10 14 103 109
45 49 101 127
60 64 89 134
70 74 73 209
75 37 173
All ages 95 108
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Percent of Population by Age
Age Pakistan U.K.
0 -14 44.5 22.2
15 64 51.2 60.0
65 above 4.2 17.8