These comprehensive slides on demography provide a deep understanding of the science of population dynamics. Covering essential concepts, methodologies, and key demographic indicators, these notes offer insights into the study of population growth, distribution, and composition. Explore topics such as fertility, mortality, migration, and population projections, as well as their implications for society and policy. With this resource, you'll gain a strong foundation in demography, making it an invaluable reference for students, researchers, and anyone interested in the dynamics of human populations.

1. Demography
BY
Ruth Mukami

2. Definition
Demography is the scientific study of the
characteristics of human populations, with
respect to their size, structure, distribution and
development

3. • Components of population
development/change are births, deaths and
migration.

4. Cont….
• Size: No of persons in a population
• Structure: the distribution of the population among its
sex and age groups
• Distribution: arrangement of population in time and
space
• Development: is the growth or decline of the total
population or of its structural units, births, deaths and
migration

5. Population
• The total number of men, women, boys and
girls, of different ages, living in a defined
location at a particular point in time

6. Demography
• It is concerned with growth, development and
movement of human population and focuses its
attention on three readily observable human
phenomena, i.e.
‣Changes in population size (growth or decline)
‣Composition of the population
‣The distribution of population in space
• Knowledge of the interaction of demographic
characteristics of a population and its health
status is important for health service providers.

7. Demography deals with five
demographic processes
‣Fertility
‣Mortality
‣Marriage
‣Migration
‣Social mobility

8. Factors In Population Dynamics
• Three factors determine the population of any defined
area:
‣Birth ( fertility)
‣Deaths (mortality)
‣Migration
• The balance of these three factors determines whether a
population decreases, remains stationary or increases in
number.
• The relation between births and deaths is referred to as
natural increase.
• When the net effect of migration is added to natural
increase this is referred to as total increase and is also
called growth rate.

9. Sources Of Vital And Health
Statistics
‣Census: is conducted every 10 years.
‣Registration: of vital events, i.e. births, deaths
and marriages
‣Notification: of diseases
‣Hospital and health facility records
‣Surveys: e.g. National Health Survey

10. Demographic Cycle
• This is the term used to describe the demographic trends of a given
country, and it passes through five stages depending on the birth and
death rates. These are greatly influenced by socio economic factors.
• The stages are:
1. High Stage (High Stationary)
• This stage is characterised by a high birth rate and a high death rate
which cancel each other and the population remains stationary.
2. Second Stage (Early Expanding)
• The death rate begins to decline, while the birth rate remains
unchanged. Many countries in South-East Asia and Africa are in this
phase. Death rates decrease rapidly as a result of improved health
conditions and sanitation.
3. Third Stage (Late Expanding)
• The death rate declines still further and the birth rate tends to fall.
The population continues to grow because births exceed deaths.

11. Cont..
4. Fourth Stage ( Low Stationary)
• This stage is characterised by low birth and low
death rate with the result that the population
becomes stationary. Zero population growth has
already been recorded in many industrialized
countries.
5. Fifth Stage (Declining)
• The population begins to decline because birth
rate is lower than the death rate.

12. DEMOGRAPHIC MEASURES
Dependency Ratio
• This measures the proportion of those economically productive to those who
are dependent:
• A high dependency ratio is a reflection of great strain on the productive
members of the population to provide for non-productive members.
Rate of Natural Increase
• This rate gives a measure of the overall gain and loss in a population through
the addition of births and the subtraction of deaths.
Fertility Rates
• Crude Birth Rate (CBR)
• This is a very rough indicator of fertility, since everyone in the population -
female, male, young, old - contributes equally to the denominator of this rate
even though only females of childbearing age are actually at risk of giving
birth.
• General Fertility Rate (GFR)
• The GFR although an improvement on the CBR, it is still affected by differences
in age composition of the female population of the reproductive age groups.

13. Developing And Developed
Countries
The characteristics of a developing country:
‣Low income
‣Inequitable distribution of wealth
‣Low literacy rates
‣Mainly rural populations
‣Mainly young populations

14. Cont…
• Some 80% of the world’s population lives in developing
countries. The population characteristics of a
developing country:
‣High birth rate
‣High infant mortality rate
‣High child mortality rate
‣High mortality rate
‣Short life expectancy
• Developed countries, in comparison, usually have
economic systems based on continuous, self-sustaining
economic growth in the tertiary and quaternary sectors
and high standards of living.

15. Demographic Projections
POPULATION
• The total number of men, women, boys and girls,
of different ages, living in a defined location at a
particular point in time

16. Cont…
• When we make a population projection, we
can estimate what a population will look like
at some time in the future and can make
comparisons between the pyramids.

17. Definition
• A population projection is defined as a “best-guess”
calculation of the number of people expected to be alive
at a future date, based on what we know about the
current population size and what we expect to happen to
births, deaths, and migration.
• Population projections are always set on a “conditional”
future because we can never be certain about the
assumptions we use in the projection. We can however
involve multiple stakeholders and experts in workshops
when we make these assumptions.

18. Why make population projections?
• ƒPlanning
– Assessing the need for new jobs, teachers,
schools, doctors, nurses, urban housing, food,
etc. ƒ
• Policy dialogue
– Helping policymakers understand that problems
exist
– Developing solutions

19. Summary of Key Population Concepts
• ƒA population is the total number of men, women,
boys, and girls, of different ages, living in a particular
place at a particular point in time. ƒ
• A population pyramid is a graphic representation of
the age and sex distribution. ƒ
• A population projection is an estimate of the number
of people expected to be alive at a future date, based
on assumptions of population size, births, deaths,
and migration. ƒ
• Population projections are useful tools for program
planning and policy dialogue.

21. This shape is typical of a developed country. It is narrow at the base, wider in the
middle, and stays quite wide until the top, as there is a sizable percentage of older
people. Note that there are more old women than men. Italy and Japan have
population structures that are of this shape.

22. Japan Population Pyramid
Significantly, the average number of children that married women are having has
remained at around 2.2 over the last three decades the decrease in fertility is almost
totally due to an increase in women of reproductive age not getting married and not
having children. This is due to a choice to stay in employment and not have children:

24. This population pyramid of the Canadian population in 1961.
You can see that the pyramid narrows toward the top. This is because the death rate is
higher among older people than among younger people.
There are also a few bulges and narrower parts in the middle part of the pyramid. For
example, there are not as many people in their 20s as in their 30s in Canada in 1961. The
people in their 20s in 1961 were born during the Depression, a time of economic hardship in
Canada when people were having fewer children.

25. Fertility
What is fertility?
• Fertility refers to the number of children born to a
women.
Why are we concerned with women and not men?
• Fertility also refers to men, but demographers have
found that it is much harder to measure the fertility
of men, and therefore, in most cases, fertility is
measured in relation to women.
• Fertility is determined by biological and social
factors

26. Measures of fertility
• There are several different measures of fertility.
• We measure fertility to estimate the number of children
that women are having in a given population during a
specific time period.
• Data used to measure fertility and other population
processes come from various sources.
• Some of these sources may produce more complete
information than others. The more information you have,
the more accurate your estimates will be.
• Some common sources for finding fertility rates include:
national fertility surveys, Demographic and Health Surveys,
Centers for Disease Control and Prevention (CDC)
Reproductive Health Surveys, the Population

27. Fertility
• The biological component of fertility is the
physical ability of a woman to reproduce
(fecundity). Over the course of her life, a
woman could bear between 13 and 17 children,
in the absence of any other factors.
• ƒThe number of children born to a woman varies
by social factors that affect when she starts
childbearing, the spacing between children, and
when she stops childbearing.

28. Measures of fertility
• The crude birth rate is the number of live births per
1,000 population in a given year. This measure tells
us how many children will be born in a given
population in a given year. It does not tell us who is
having children, or how many children the typical
woman might have
Crude birth rate (CBR):
• The number of live births per 1,000 persons in a
given year
• CBR = ( # births in a year ) X 1000
Mid-year population

29. Measures of fertility
Age-specific fertility rate (ASFR):
• The number of births occurring annually per 1,000 women of a
specific age (usually given in 5year age groups)
Total fertility rate (TFR):
• The approximate number of births that a woman will have if she
moves through her reproductive years having births at the
current age-specific birth rates.
• ƒTFR is a synthesis measure of the number of births women of
different ages are having now
• TFR is the sum of the age-specific rates (ASFRs) multiplied by 5
and divided by 1000.
• ƒTFR is expressed as a rate per woman.
• ƒTFR can be compared across populations because it is not
influenced by differences in age structure.

30. Cont..
Replacement level fertility:
• The TFR at which women have exactly the number of
births required to replace themselves and their partners.
• If no children died before reaching adulthood,
replacement level fertility would be 2 births per woman
(1 to replace the mother and 1 to replace her spouse). If
death rates are low, replacement-level fertility averages
about 2.12, since not all children will survive to reach
reproductive age. If mortality rates are high,
replacement-level fertility will be higher.

31. Cont..
Sex ratio at Birth ƒSex ratio at birth:
• The number of male births per 100 female
births.
• ƒIn most countries, this value is 103–105,
which means that for every 100 girls born,
there are between 103 and 105 boys born.

32. MORTALITY
Mortality and Population Growth ƒ
• Declining mortality (and not rising fertility) has
been the cause of the accelerating pace of
world population growth.

33. Measures of Mortality
ƒ
Crude death rate (CDR):
• The number of deaths in a given year, per 1000
people in the population in the middle of that
year.
• CDR = ( number of deaths ) X 1,000
mid-year population
Infant Mortality Rate (IMR):
• The number of deaths to children under 1 year of
age per 1,000 live births in the same year.
• IMR = No. of deaths to children < 1 yr X 1,000
number of live births

34. Cont..
Under five mortality rate (U5MR):
• The number of deaths to children under the age
of five per 1,000 live births in a given year.
Life expectancy at birth:
• The average number of years a new cohort of
infants can expect to live based on current
mortality conditions.
Maternal mortality ratio (MMR):
• The number of women who die due to pregnancy
and childbirth complications per 100,000 live
births in a given year.

35. Cont..
Life Tables
• ƒ
Life tables tell what would happen to a new
birth cohort if the current age-specific death
rates were to remain constant over its entire
lifetime experience. ƒ
• Life tables give the distribution of deaths that
would occur within each age group. ƒ
• Life tables also produce values for life
expectancy.

36. MIGRATION
• There are other measures of a population that
help us understand population projections.
The size of a population is not only affected by
births and deaths but is also affected by the
number of people coming into and out of a
place.

37. Measures of migration
• Measuring Migration ƒPeople move different
distances. ƒ
• Some migrants are ‘return migrants.’ ƒ
• Some migrants are not official/legal and may
view their ‘residence’ differently.
• Generally, migration is more difficult to measure
than fertility and mortality because of some
complexities noted here. First, we need to define
whether we are trying to measure domestic or
international migration. People move within the
country all the time

38. Cont..
Net migration:
• The difference between those who move in and those who move
out of an area
NB:
• Negative net migration implies that there are more people moving
out than in. ƒ
• Positive net migration implies that there are more people moving in
than out. ƒ
• Zero net migration does not necessarily mean that nobody is
moving in or out of an area.
• Net international migration is not a major component of population
change in most countries. ƒ
• Age and sex patterns of migration vary considerably. ƒ
• Net migration can be temporary or can vary throughout the year.

39. POPULATION GROWTH
Population Growth Concepts: ƒ
• Net migration:
• The difference between the numbers moving in
and the numbers moving out of a defined area.
• ƒNatural Increase:
• The difference between the numbers of births and
deaths in a defined population.
• Population Growth Rate ƒ
• Population growth is the percentage change in the
size of the population in a year. ƒ

40. Population Momentum
• ƒMomentum is the tendency for a population to continue
to grow even after replacement-level fertility has been
achieved.
• ƒPopulation momentum occurs because the age structure
has large numbers of women in the childbearing years,
so there are many more births than deaths for a long
time to come.
• ƒTherefore, even when replacement-level fertility is
achieved, it can take the population growth rate a long
time to reach zero!
• Population momentum is mainly a function of a
population’s age structure.
• In other words, the larger the number of children
entering their reproductive years, the faster the
population will grow

41. CONT..
Methods of Calculating Population growth
• Components of growth method
• ƒCohort component method
Components of Growth Method
• 3 demographic processes influence population
change: Birth, Deaths and Migration
• Pop (2) = Pop(1) + Births – Deaths + Migrants(in) –
Migrants(out)

42. Cont..
Cohort component method ƒ
• It begins with an age/sex population distribution
for a base year ƒ
• It uses base year age-specific rates (fertility,
mortality, net-migration)
– Data are usually arranged in 5-year age
intervals ƒ
• It makes assumptions about the future course of
each component of population growth

43. Vital Health Statistics
• Vital statistics is the numerical description of
birth, death, abortion ,marriage ,divorce,
adoption and judicial separation

44. Components of vital statistics
• Demography
• Vital events
• Environmental health statistics
• Communicable disease
• Non-communicable diseases
• Health status like mortality, morbidity, disability,
quality of life.
• Health resources like facilities, beds, manpower

45. Uses of vital health statistic
 To evaluate the impact of various National
Health Programmes.
 To plan for better future measures of disease
control.
 To explain the heridetary nature of the
disease.
 To plan and evaluate economic and social
development

46.  it is a primary tool in research activities.
 To determine the health status of individual.
 To compare the health status of individual one
nation with others

47. Sources of Vital Statistics
• Civil Registration System: Civil registration is
performed under a law and regulation so as to
provide legal basis to the records and
certificate made from system likes live births,
deaths, fetal deaths, marriages, divorces

48. • Health Surveys: A few important sources for
demographic data have emerged. These are
National Family Health Surveys(NFHS) and the
District Levels Household Surveys(DLHS)
conducted for evaluation of reproductive and
child health programmes.

49. • Population Census
• Population Census
• Civil Registration System
• Hospital records
• Sample Registration System
• Sample Surveys

50. Descriptive Statistics
Descriptive statistics are used to describe
frequency distribution, measures of dispersion
(or variability), standardised scores and
measures of central tendency.

51. Frequency Distribution
• This is a method used to organise data in
tabular form according to the frequency of
their occurrence. There are two types of
frequency distribution: Ungrouped and
Grouped.

52. Ungrouped Frequency Distribution
• Ungrouped frequency distribution lists variables
in the form of a column of the values and the
frequency of occurrence of the values. It is used
when dealing with discrete data or variables.
Discrete data are types of variables that can only
take whole number values, such as the daily
attendance in your health facility or the number of
syringes in a box. Obviously, you can not have
13.5 people attending your clinic or 30.4 syringes.
Consider the following example

54. Grouped Frequency Distribution
• Grouped frequency distribution is used when
there are a large number of figures with many
values and frequencies. The values are
grouped in what is known as 'class intervals'
(for example 0-5 years) thus making the data
easier to understand.

56. Application Of Statistics
• Statistics helps in providing a better understanding and exact
description of a phenomenon of nature.
• Statistical helps in proper and efficient planning of a statistical
inquiry in any field of study.
• Statistical helps in collecting an appropriate quantitative data.
• Statistics helps in presenting complex data in a suitable tabular,
diagrammatic and graphic form for an easy and clear comprehension
of the data.
• Statistics helps in understanding the nature and pattern of variability
of a phenomenon through quantitative observations.
• Statistics helps in drawing valid inference, along with a measure of
their reliability about the population parameters from the sample
data.

57. Types Statistical of Data
• Quantitative research deals with numbers
and statistics, while qualitative research deals
with words and meanings. Quantitative
methods allow you to test a hypothesis by
systematically collecting and analyzing data,
while qualitative methods allow you to
explore ideas and experiences in depth.

58. Types of statistics:
• Descriptive Statistics
• Inferential Statistics

59. Descriptive Statistics:
In descriptive statistics; it deals with
collection of data, its presentation in various
forms, such as tables, graphs and diagrams and
findings averages and other measures which
would describe the data.

60. Types of Descriptive Statistics
• Descriptive statistics allow to characterize data
based on its properties. There are four major
types of descriptive statistics.

61. Measures of Frequency:
• Count, Percent, Frequency
• Shows how often something occurs
• Use this when you want to show how often a
response is given

62. Measures of Central Tendency
• Mean, Median, and Mode
• Locates the distribution by various points
• Use this when you want to show how an
average or most commonly indicated response

63. • Mean; is the sum of all observations divided
by the number of observations.
• Method for calculating the mean
• Step 1. Add all of the observed values in the
distribution.
• Step 2. Divide the sum by the number of
observations

64. • Median
• The median is the middle value of a set of data
that has been put into rank order. the statistical
median is the value that divides the data into
two halves, with one half of the observations
being smaller than the median value and the
other half being larger. The median is also the
50th percentile of the distribution.

65. • Method for identifying the median
• Step 1. Arrange the observations into increasing or
decreasing order.
• Step 2. Find the middle position of the distribution
by using the
• following formula: Middle position = (n + 1) / 2
• a. If the number of observations (n) is odd, the
middle position falls on a single observation.
• b. If the number of observations is even, the middle
position falls between two observations.

66. Mode
• It is the value of the observation that occurs
with the greatest frequency. It can be
determined simply by tallying the number of
times each value occurs.

67. Measures of Dispersion or Variation
or spread
• Range, Variance, Standard Deviation
• Identifies the spread of scores by stating
intervals
• Range = High/Low points
• Variance or Standard Deviation = difference
between observed score and mean.

68. • Range
• The range of a set of data is the difference
between its largest (maximum) value and its
smallest (minimum) value. In the statistical world,
the range is reported as a single number and is the
result of subtracting the maximum from the
minimum value

69. Definition of standard deviation
• The standard deviation is the measure of
spread used most commonly with the
arithmetic mean

70. • Method for calculating the standard deviation
• Step 1. Calculate the arithmetic mean.
• Step 2. Subtract the mean from each observation.
Square the
• difference.
• Step 3. Sum the squared differences.
• Step 4. Divide the sum of the squared differences by
n –
1.
• Step 5. Take the square root of the value obtained

71. Measures of Position or measure of
relative position
• Percentile Ranks, Quartile Ranks

72. • Inferential Statistics:
• In inferential statistics, it deals with
techniques used for analysis of data, making
the estimates and drawing conclusions from
limited information taken on sample basis and
testing the reliability of the estimates.

73. Types of Inferential Statistics
• The methods of inferential statistics are:
1.The estimation of parameter statistics, estimation refers to the
process by which one makes inferences about a population,
based on information obtained from a sample
2. Testing of statistical hypotheses A statistical hypothesis is an
assumption about a population parameter. This assumption
may or may not be true