INTRODUCTION TO POPULATION
STUDIES
By:Seifadin A.(MPH/RH)
Objectives
After Completing this chapter the learner is able to:
 Define Demography
 Identify the different sources of demographic data
 Explain the differences between the major sources of
data
 List and state steps needed in conducting population
census.
What is demography?
• It is the study of human populations including their composition,
distributions, densities, growth and
•
other characteristics as well as the
causes and consequences of changes in these factor
• Focuses on three area of ppln phenomena
• Changes in population size (growth or decline)
• The composition of the population and
• The distribution of population in space.
From where can we can get Demographic
Data?
• Demographic data are important for:
• Policy making, for economic purpose,
• In identifying needs(health service, education,
employment)
The major sources of demographic data??
The major sources of demographic data include
Census
 Registration of vital events (Records)
Sample surveys
Ad-hoc Demographic studies
1. What is Census?
• It is enumeration or complete population
count at a point in time
• within a specified geographical area.
• A census provides more reliable and accurate
data
• There are two techniques of conducting census,
• dejure and defacto.
A.Dejure
This technique is the counting of people according to the
permanent place of location or residence.
Advantages
• It gives permanent picture of a community.
• It provides more realistic and useful statistics.
Disadvantages
 Some persons may be omitted from the count.
 household member who is temporarily away from
home may be missed from being counted
 Counting twice
 Incomplete info about peoples not around .
B.Defacto
• refers to counting persons where they are present at the
time of the census period.
• Advantages
• There is less chance for the omission of persons from the
count.
• Disadvantage
• Difficult to obtain information regarding persons in
transit.
• Over or Under estimate population in given area
• Distort the vital statistics of a community
Uses of Census
A census is useful for:
• Planning
• Calculating health indicators and vital indices.
Steps in Conducting Census
• Planning and preparation
• Collecting information
• Compilation and analysis
• Evaluation
Qualities of a Census
 It should include every individual in the area (no
omission or duplication).
 Information should relate to a well – defined point
in time.
 It should be taken at regular intervals (preferably
every 10 years).
 It should refer to people inhabiting a well defined
territory.
 Information be obtained from personal contact.
2. Registration of Vital Events (Statistics)
• It is a regular and continuous registration of
vital events
• which records births, deaths, marriages
etc. (vital statistics),
• It enables rates of population growth to be
calculated;
• but are much less adequate than national
censuses.
3. Sample Surveys
• carried out in a scientifically selected area
which covers only a section or portion
(sample) of the population under
consideration.
• Discuss
• What do you think the difference between
Census and Sample Survey??
• (2 Minutes)
Test Your Memory
• Study Questions
1. What is Demography?
2. Name and explain the different sources of
demographic data?
3. State the steps that should be fallowed to
undertake a population census.
4. Explain the advantages and limitations of
sample surveys.
TOOLS AND TECHNIQUES
in demographic measurement
After completing this chapter the learner is able
to:
 Stat the measurements used in demographic data
 Calculate ratios, proportions and rates and
discuss their importance
 List and calculate the different measures of
fertility and mortality
Tools of Measurement in demography
The tools of measurement of different
demographic events include:
• Ratios
• Proportions and
• Rates
• Ratios: Ratio is a quecient of any two
demographic quantities.
• It is the result of dividing one quantity by
another.
• Ratio quantifies the magnitude of one occurrence
or condition in relation to another. It is
expressed in the form of:
a/b , or a ; b
e.g. sex ratio(male to female) (1:1.2)
• Doctor to Population ratio=
=No. of doctor/No. of population
• Qualification:
• The numerator and denominator (a and b)
are defined for a specific geographic area and
period of time.
• The numerator may or may not be a sub –
group of the denominator.
• Proportion: A proportion is a ratio which
indicates the relation in magnitude of a part of
the whole.
• The numerator is always included in the
denominator.
• A proportion is usually expressed as Percentage
(%)
Example: Males to total population ratio
= Males x 100
Males + females
• Rates:
• measures the occurrence of some particular
event (example, death) in a population
during a given time period.
• It is a statement of the risk of developing a
condition.
• It indicates the change in some event that
takes place in a population over a period of
time.
• It is defined per unit of time.
• Rate =Numerator
(Vital event) X (K)
Denominator (Population at risk)
• K=10n can be 100 or but commonly (1000)
• Example:
• Death Rate = No. of deaths in one year X 1000
Mid year population
• A rate comprises the following elements:
• Numerator
• Denominator
• Time specification and
• Multiplier or constant (100, 1000, 10000, 100,000 etc)
Techniques of Demographic Measurement
• A change in the overall size of a population is
the result of three cumulative changes
 changes in number of
• births, (fertility)
• Deaths(Mortality) and
• migrants.
Measure of Fertility and Mortality
Fertility measures
•
 Crude Birth Rate (CBR)
•
 General Fertility Rate (GFR)
 Age specific fertility rates
•
(ASFR)
 Total Fertility Rate (TFR)
 Gross Reproduction Rate •
(GRR)
 Child – Woman Ratio
•
(CWR)
Mortality measures
Crude Death (Mortality)
Rate (CDR)
Age specific Mortality
rate (ASMR)
Maternal Mortality
Rate(MMR)
Sex Specific Death Rates
(SSDR)
Measure of Fertility
• Fertility is the reproductive performance of an individual, a
couple, a group or a population.
• It is meant the actual bearing of children.
• Some demographers prefer to use natality in place of
fertility.
• fecundity – which refers to the physiological capability of a
woman to reproduce.
Crude Birth Rate (CBR)
• CBR = Number of live births in a year X 1000
Total mid – year population
General Fertility Rate (GFR)
• GFR = Number of live births in a year X 1000
Number of females 15-49 years of age
 more sensitive measure of fertility than the CBR,
 not all women in the denominator are exposed to
the risk of child birth(Limitation).
 is approximately four times the CBR.
Age specific fertility rates (ASFR)
• ASFR =No. of live births to females in a specific age
•
group in a year X
1000
Mid-year population of females of the same age group
• For instance if there were 4,000,000 women (females) in the
age group 20-24 years and if the there were 200,000 live births
to women in the same age group, the Age specific fertility rate
for these women (20-24 years of age) will be;
• ASFR (20-24) years of age = 200,000 X 1000 = 50
4,000,000
 That is, there are 50 live births for every 1000 women
20-24 years of age.
Total Fertility Rate (TFR)
• TFR is the average number of children that
would be born to a woman throughout her life time or
her child bearing age (15-49 years),
• if she were to pass through all her child bearing years
at the same rates as the women now in each age
group.
• TFR sums up in a single number the ASFR of all
women at a given point in time and multiply by age
interval (Usually 5 years)
• This measure gives the approximate magnitude of
“completed family size”.
• The TFR is one of most useful indicators of fertility,
• because it gives the best picture of how many
children women are having currently.
TFR = Sum of all ASFR rates multiplied by age
interval. Usually 5
• What do you think the TFR of Ethiopia now??
• What should TFR be to replace the it self?
Look following examples:
-
• The Gross Reproduction Rate (GRR)
• is the average number of daughters that would be born to a
woman throughout her Lifetime or child bearing age (15-49
years), if she were to pass through all her child bearing age.
GRR = TFR X Female births
Male + Female births
• literally measures “reproduction”; a woman reproducing
herself by having a daughter.
Example:
• - The sex ratio at birth of Ethiopia (2001) = 100.6
(i.e. 100.6 males for every 100 females)
- and the TFR (2001) = 5.9 (5.9 children per
women)
GRR = TFR X proportion of female births
GRR = 5.9 X 100 = 2.94
200.6
= 2.9 daughters /woman
Measures of Mortality (Death)
 Measures reduction of population
 Incidence of death can reveal much about the
living standard,
the health status of a population and
the availability of health services
Mortality (Death) rates have three essential elements:
A population group exposed to the risk of death
(denominator)
The number of deaths occurring in that population
group (numerator)
A time period.
Crude Death (Mortality) Rate (CDR)
• CDR = Total number of deaths in a year X1000
Mid-year population
• CDR is not a sensitive measure (indicator) of health status of a
population
Age specific Death (Mortality) Rates
ASMR = Number of deaths in a specific age group X1000
Mid-year population of the same age group
• Infant Mortality Rate (IMR)
• Child Mortality Rate (CMR)
• Under Five Mortality Rate (<5MR
• Neonatal Mortality Rate (NNMR)
•
Sensitive indicators for
•
Community
Health Problems
•
Neonatal Mortality Rate (NNMR)
•
Neonatal mortality rate reflects mortality due to:
 Maternal factors during pregnancy
 Birth injuries
 Neonatal infection, etc.
 It is an indicator of the level of prenatal and obstetric components of maternal
and child health care (MCH).
NNMR= Number of deaths of infants < 1 month in a year X 1000
Total number of live births in the same year
post-neonatal mortality rate
• The post-neonatal mortality rate reflects
deaths due to factors
related to;
• Environmental sanitation
• Infections (communicable diseases)
• Nutritional problems
• Child care etc.
Under five mortality rate(1-4 age)
• <5MR =
Number of deaths of children <5 yrs in a year X 1000
Total number of children < 5 years of age
OR
•
< 5MR =
Number of deaths of children <5years in a year X 1000
Total live births in the same year
Maternal Mortally (Death) Rate
(MMR)
• Maternal mortality rate is the number of maternal deaths
related to pregnancy, child birth and post natal (peurperium)
complications
•
MMR = Number of deaths of women related to pregnancy
child birth X 100,000
Total number of live births in the same year
• It is a sensitive indicator of health status of a population.
• It reflects the socio- economic status of a community.
• Sex Specific Death Rates (SSDR)
SSD(Mortality) Rate for males
= Number of deaths among males X 100
Total number of males
used to determine which sex group is at higher
risk of death than the other.
Test Your Self!
1. What are ratios, proportions and rates? Explain their
differences.
2. Distinguish the difference between natality, fertility
and fecundity
3. List and define the important demographic measures
of fertility and mortality.
POPUALTIONS GROWTH
Population Dynamics
- is the study of the changes in population
size and structure over time.
- Population growth- is change of population over time
Population size: Future projections
Demographers project population growth trends to estimate
future population sizes.
Different fertility rate scenarios predict global population
sizes in 2050 of 7.4 billion, 8.9 billion, or 10.6 billion.
All these projections assume fertility rates below today’s; at today’s rate, the population would
reach 12.8 billion.
Figure 7.7
World population has risen sharply
•
•
•
•
Global human population was <1 billion in 1800.
Population has doubled just since 1963.
We add 2.5 people every second (79 million/year)
Today about 7.7 billion (2018)
Figure 7.2
Age structure: Age pyramids
Canada (left) has a much slower growing population
than does Madagascar (right).
Figure 7.10
Is population growth really a problem?
Some say NO:
Some say YES:
• People can find or
manufacture additional
resources to keep pace
with population growth.
• Nations become stronger
as their populations
grow.
• Not all resources can be
replaced.
• Even if they could,
quality of life suffers.
• Nations do not become
stronger as their
populations grow.
Factors affecting population growth
Population growth depends on rates of birth, death, immigration,
and emigration.
Total Population Growth Rate
It is the rate at which a population is increasing (or decreasing)
population growth rate = (birth rate + immigration rate)
– (death rate + emigration rate)
TGR= Natural increase + Net Migration X 100
Total Population
Population size at given time is calculated as
Pt = P1 + ( B – D) + ( I - E)
Where:Pt = Size of population for the year under
consideration
P1 = Size of population in the preceding year
B = Number of births between the two times
D = Number of deaths between the two date.
I = Number of immigrants in the time under
consideration (between Pt and P1)
E = Number of emigrants in the time under
consideration (between Pt and P1)
Natural rate of population change
RNI=Change due to birth and death rates alone,
excluding migration
RNI = Births - Deaths X 100
Total Population
or Birth Rate - Death Rate
=Is often expressed in % per year
Population projection
• Based on the total rate of increase (r), the population (Pt) of
an area with current population size of (Po) can be projected
at some time (t) in the short time interval (mostly not more
than 5 years) using the
following formula.
Pt = Po(1+ r)t
• For example if the CBR=46, CDR=18 per 1000
population and population size of 25,460 in 1998, then,
what will be popln. Size at 2003??
• Assuming net migration is zero
Population doubling time
• The doubling time of the size of a population can be
estimated based non the formula for projecting the
population
or Doubling Time = ______0.7_________
Population Growth Rate
What will be the popln doubling time for the above example?
• Note: Doubling time cannot be used to project future
population size
Types and reasons for population
growth
• Geometric growth:-if the change within a particular year is
proportional to the population size at the beginning of that
year.
• E.g. 3,9,27,..
• Arithmetic growth:if the size changes by a constant amount each year
• E.g. 1,2,3…
• The doubling time of a population is the number of years it
would take for a population to double in size if the present
rate
of growth remained unchanged.
population growth form
• Populations have characteristic patterns of increase which are
is termed as population growth form
 Of two types
a) Exponential Growth Form (J - Shaped Growth Curve)
 when there is no environmental restrictions, density increases
rapidly in exponential form.
 then stops abruptly as environmental resistance or other
limits of resources become effective more or less suddenly
J-shaped growth
Sigmoid Growth Form (S - Shaped)
• In this growth form the population increases slowly at first
(establishment or positive acceleration),
• then increases more rapidly (perhaps approaching a
logarithmic phase),
• but soon it slows down gradually as the environmental
resistance
(S – Shaped) growth
Demographic transition theory
Demographic transition = model of economic
and cultural change to explain declining death
rates, declining birth rates, and rising life
expectancies in Western nations as they
became industrialized
Proposed by F. Notestein in the 1940s-1950s
Demographic transition: Stages
Figure 7.18
Female education and TFR
Female literacy and
school enrollment
are correlated with
total fertility rate:
More-educated
women have fewer
children.
Figure 7.16
Family planning and TFR
Family planning, health care, and reproductive
education can lower TFRs.
A counselor advises African women on health care and
reproductive rights.
Figure 7.17b
Family planning and TFR
Nations that
invested
in family
planning
(green)
reduced
TFRs more
than
similar
nations
that did
not (red).
Figure 7.17a
HIV/AIDS and human population
AIDS cases are increasing rapidly worldwide.
Figure 7.26
HIV/AIDS and human population
Infects 1 in 5 people in southern African nations
Infects 5 million new people each year
Kills babies born to
infected mothers
Has orphaned
14 million children
• Has cut 15 years off
life expectancies in
parts of
southern Africa
Figure 7.27
Poorer countries will experience most
future population growth
98% of the
next billion
people born
will live in
developing
nations.
Figure 7.20