1. GlobalDemography:Population,
Urbanization,andEcology
Sir Malit

2. What is Population?
Population and Ecology are closely
related to each other. The growth of
population can be a burden to the
environment, depleting its resources
and threatening human and animal
life.
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3. What is demography?
Demography refers to the scientific
study of the size, composition,
distribution and changes in human
population. Demographic studies
describe the composition of a
population by its distribution of
population categories such as race,
age, marital status, gender,
socioeconomic status, and religion.
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4. What is demography?
Demographers seek to know the
levels and trends in population size
and its component. They search for
explanations of demographic change
and their implication for society. They
use census birth and death records,
surveys, visa records, even motor
vehicle and school registration.
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5. Thetoolsof
Demography
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6. Count
This refers to the absolute
number of a population or
any demographic event
occurring in a specified area
in a specified time period (for
example, 1,200,500 live
births occurred in Japan in
1977). The raw quantities of
demographic events are the
basis of all other statistical
refinements and analyses. 6

7. Rate
The frequency of demographic events
in a population during a specified time
period (usually a year) divided by the
population “at risk” of the event
occurring during that time period.
Rates tell how common it is for a
given event to occur (for example, in
1997 in Papua New Guinea, there
were 34 live births per 1,000
population). Most rates are expressed
per 1,000 population.
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8. Ratio
The relation of one population
subgroup to the total population or to
another subgroup, that is, one
subgroup divided by another (for
example, the sex ratio in Iran in 1996
was 103 males per 100 females).
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9. Proportion
The relation of population subgroup
to the entire population, that is, a
population subgroup divided by the
entire population (for example, the
proportion of Malaysia’s population
classified as urban was .57 or 57%).
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10. Constant
An unchanging, arbitrary number by
which rates, ratios, or proportions can
be multiplied to express these
measures in a more understandable
fashion.
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11. Cohort Measure
A statistic about measures events
occurring to a cohort (a group of
people sharing a common
demographic experience) who are
observed through time. The most
common used cohort is the birth
cohorts– people born in the same
year or period. Other kinds of cohorts
include marriage cohorts and school
class cohorts.
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12. Period Measure
A statistic that measures events
occurring to all part or part of a
population during one period of time,
this measure “takes a snapshot of a
population, in effect (For example, the
death rate of the entire Canadian
population in 1997 was 7 per 1,000).
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13. About
Population
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14. Population Composition and
Density
Population density can be expressed as a ratio
between the number of people and a particular unit
of measure. The most common of such measures is
crude or arithmetic density. To arrive at the crude
population density of a place, it is necessary to divide
the total number of people who live there by the
total land area. The United States, for example, has
an average population density of about 84 people per
square mile. New York City, however, has a population
density of 23,671 people per square mile, whereas
some parts of Alaska have population densities of
near zero people per square mile. Therefore, crude
density is a very general measurement of population
distribution. In order to get a more accurate picture
of the population densities and the significance of
variance in demographic characteristics throughout
the world, we must turn to other measures such as
agricultural density, nutritional density, age-sex
pyramids, and birth/mortality rates.
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15. Fertility,
Mortality,and
Migration
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16. Fertility
In terms of populations rather than individuals,
fertility is usually expressed using the proxy measure
of birth rate, either crude or standardised for age and
sex. Worldwide, there are significant differences
between birth rates. A major study in the 1980s,
carried out by the Population Division of the
Department of International Economic and Social
Affairs of the UN Secretariat, studied the relationship
between population age and sex distribution and
crude fertility rates for twenty one countries in the
developing world. They concluded The higher the
birthrate the more markedly the birthrate is
depressed by the age structure. All other things being
equal, fertility should decline more rapidly in the
countries where it is currently lowest since the age
structure appears to favor such a course.
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17. Fertility
The mean number of children ever born also ranged
widely among the twenty one countries. Differences
in completed family size range from 8.6 children in
Jordan to 5.2 children in Indonesia. 1 In the
developed world, though, there is a global tendency
for family sizes on average to be smaller than the
replacement level. The “replacement level of fertility”
is the number that causes a country’s population to
slow down and eventually stabilize. According to the
CIA World Factbook's 2014 data the Total Fertility
Rate for women is below 2 children for North
America, Brazil, all the EU states except France,
Russia, China, and Australasia, while women in most
of sub-Saharan Africa has between 3 and 7 children
on average.
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18. Mortality
The effect of mortality on population structures is to
reduce the component of the population in which the
mortality occurs. Historically, the most dangerous
ages were infancy and old age (variously reckoned
according to circumstances). In addition, some
epidemics of infectious diseases (e.g. Spanish 'flu)
had their highest mortality among young adults,
whose immune systems were presumably
insufficiently primed. It is expected that the forecast
bird 'flu epidemic will behave similarly. War
differentially reduces the proportion of younger men.
The majority of infectious diseases of early childhood
have been reduced by immunisation, and improved
nutrition and hygiene have rendered childhood safer.
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19. Mortality
Antibiotics, welfare state, and improvements in
medical, surgical, and palliative care have resulted in
great increases in life expectancy in the developed
world, where life expectancy is now in the middle to
upper 70s or lower 80s, and rising every year. The
effect of this is to raise the population in the upper
age groups substantially. Women have higher life
expectancy than men wherever they live. The
tendency of people to retire to particular resorts
means that in some parts of the South Coast of
England the average (arithmetic mean) age of the
population is only just below retirement age.
The down side of this is that the extended lives are
often lived in bad health, as the treatments people
receive may keep them alive but do little to
ameliorate the underlying pain or disability brought
on by the diseases, and virtually nothing for the
various forms of senile dementia that are increasingly 19

20. Migration
This has been less studied. In areas where natural
disasters or politico-military concerns lead to entire
populations being displaced the initial population
structure will be unchanged, though post-migration
the population will have altered to reflect those who
have survived the process, typically showing
increases in older children and younger adults.
Opportunistic migration tends to occur mostly among
younger adults, and may be permanent or temporary.
Some studies have shown increased fertility levels in
migrants, so the effect of migration on population
structure is to deplete the population emigrated from
in the young adult groups, to augment this group in
the immigrated-to population, and to increase the
fertility/birthrate in the new population.
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21. World Population
(As of July 1, 2019)
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World Population
7,610,184,021
Source:
https://www.census.gov/popclock/print.p
hp?component=counter
Country Population
China 1,389,618,778
India 1,311,559,204
United States 331,883,986
Indonesia 264,935,824
Pakistan 210,797,836
Brazil 210,301,591
Nigeria 208,679,114
Bangladesh 161,062,905
Russia 141,944,641
Mexico 127,318,112

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