Demography uph

1. DEMOGRAPHY
Prof Hla Hla Win
Head, Biostatistics department, UPH
Head, PSM department, UM 2

2. What is Demography?
Scientific study of Human population
Changes in population size
Composition
Distribution of population in space
The broader field of population studies embraces the
questions of why these changes occur, and with
what consequences

3.  Size
 Distribution
 Composition
 Population dynamics
 Socio-economic determinants and consequences of
population change

4. Consider:
 Interrelationship with population change and
human health

5. Global issues
 the world’s population is growing at an unprecedented rate

6. Demographic process
 Fertility
 Mortality
 Marriage
 Migration
 Social mobility

7. Demographic cycle
 First stage ( High stationary )
 Second stage ( Early expanding)
 Third stage ( Late expanding )
 Fourth stage ( low stationary)
 Fifth stage ( declining )

8. Demographic indicators
 Population statistics : population size, sex ratio,
density, dependency ratio
 Vital statistics : Birth rate, Death rate, natural
growth rate, life expectancy at birth, mortality rate,
fertility rate

9. Family size
 Total number of children a woman has borne at a
point in time
 Family size depends on ……?
 Family planning norms; two child family norm
with a view to reach long term demographic goal of
NRR=1

10. 10
Currently data on population is
utilized/used by;
 Businesses
 Governments
 Academicians

11. 11
Businesses;
Businesses use population data to;
 Identify potential markets & places to run
advertisements (retail businesses).
 Determine whether an area considered for a
plant/factory has a sufficient labour force.
 They also study population shifts for changes
that could affect market for their products,
(manufacturing businesses).

12. 12
Government;
 Governments at all levels also utilize population data
for the following purposes;
 1. For long range planning of various departments &
government organizations.
 2. For projecting the kind of public services that
will be needed at various points in the future.
 3. For monitoring changes in society such as decline
or improvement in health, shifts in the structure of
the family, alterations in ethnic relationships etc.

13. 13
Government –contd:
4. 4. For health planning. Demographic data can assist in
helping to plan by describing the following;
 Uptake of health services in a country or an area.
 The usual presentation of illnesses in an area/country.
 By identification of the population’s perception of illness &
disease.
 By identifying the lifestyle & cultural practices of the
population.
 By the kind of encounters that the population has with the
services.
 By identifying the patterns of disease in the population.
 By identifying the kind of alternate medicine being utilised by
the population.

14. 14
Academicians;
 Academicians use demographic data;
  To improve understanding of human society by
analyzing the consequences of social political & economic
change brought about by population alterations. In so
doing they
  Help to forecast the future of the society.
  Assist governments in planning purposes.

15. Use
1. Future needs of the community
2. Evaluating existing services and programs
3. Planning and administration of programs
Sources
census, disease notification, vital registration,
hospital and health service reports & records,
surveys, sickness and absentee records

16. Quality of information varies according to country or
source, and it makes comparison difficulties
Problems are;
1. Absence of uniform and standard method of
collection
2. Lack of completeness in coverage and with
respective to data collection form
3. Inaccuracies in recording
4. concealment, under-notification and inaccurate
diagnosis

17. Measurement tools
(a)actual count
(b)rate
(c)ratio
(d)proportion
Rates – 1. crude rate = total population without regard
to any specific characteristic
2. specific rate = defined in terms of one or
more characteristics

18. THE CENSUS
Definition
Total process of collecting, compiling and publishing
demographic, economic and social data pertaining at a
specific time to all persons in a country or delimited
territory.
•census obtains information about the number of
population as well as age, sex, housing, education,
income, etc.
• mostly interval of ten years

19. • Two types
(a) De facto method = all persons in an area on the
census date.
(b) De jure method = all persons who usually reside in
a particular area.
• data collection methods
(a) Canvasser or enumerator method = data collection
by trained enumerators.
(b) Householder or questionnaire method = head of
household completes a questionnaire.

20. (a): de facto census :counting individuals wherever they
actually are on the day the census is conducted. The de facto
census is much easy, less expensive and more economic to
apply than de-jure type.
The disadvantages include
1- Persons in transit may not be included
2- Provision of incorrect picture of the population
3- Vital rates may be distorted
(b):The de jure census, counting individuals at their legal
permanent residence regardless to whether or not they are
physically present at the time of the census. It gives a true
figure.
The disadvantages include
1- Expensive in time and money
2- Some individuals may be counted twice
3- Information may be incomplete

21. Young geographically mobile adults, members
of minority ethnic groups, infants, and the very
old are the groups most likely to be under-
enumerated.
differential age misreporting between
census and other sources,

22. • Intercensal and postcensal period= use estimation
1. Arithmetic method = increase by equal count in equal
period of time
Pn = P0 + nI
2. Geometric method = increase by equal rate in equal
period of time
Pn = P0 (1 + r)n
3. Natural increase method = based on the number of birth
and death, in-migration and out-migration
Pn = P0 + (birth - death) + (in-migration – out-migration)
Pn = population at “n” years after last census
P0 = population at last census
I = count of yearly increase
r = yearly increase rate
n = number of years after last census

23. World population growth
• highest growth rate in human history = about 2%
• absolute number (nowadays) = 6 billion
• adding nearly 80 million per year
• growth rate never reached (0.1%) until late 17th
century

24. POPULATION TRANSITION
Theory = based on fertility and mortality
1st Stage (High stationary) = high fertility + high mortality =
population remains stable
2nd Stage (Early expansion) = birth rate remains high while
death rate begins declining = population starts to increase
3rd Stage (Late expansion) = death rate continues to fall, birth
rate begins to decline = expansion with low increase
4th Stage (Low stationary) = low fertility + low mortality =
population becomes stationary
5th Stage (Decline) = low fertility + low mortality, but lower
fertility = population starts to decline

25. Death
Birth
1st
Stage
2nd
Stage
3rd
Stage
4th
Stage
5th
Stage
(Population Transition)

26. Population Age-Sex Composition
• relative number of people in different age and sex
classes
• well displayed by population pyramid
• developing countries = large number of <15 and
small number of =>65, due to high birth rate
• sex ratio = almost constant and not much effected by
natural increase
• variation sex ratio may be d/t selective migration and
morbidity

27. • Age heaping
• Sex differential
• Demographic transition
• Epidemiologic transmission

28. Uses of census
• Provides evidence of past events in the population
• Ecological process may leave marks on the
population structure
• Existing structure may influence future ecological
development
• Allows assessment of the limits of organizational
development in the particular population

29. Male Female
21 18 15 12 9 6 3 0 3 6 9 12 15 18 21
Population (%)
>60
40-60
>18-40
>5-18
>3-5
>1-3
0-1
Age
Group
Population age-sex structure

30. Male Female
21 18 15 12 9 6 3 0 3 6 9 12 15 18 21
Population (%)
>60
40-60
>18-40
>5-18
>3-5
>1-3
0-1
Age
Group
Population age-sex structure

31. Male Female
21 18 15 12 9 6 3 0 3 6 9 12 15 18 21
Population (%)
>60
40-60
>18-40
>5-18
>3-5
>1-3
0-1
Age
Group
Population age-sex structure

32. 1999 2000
21 18 15 12 9 6 3 0 3 6 9 12 15 18 21
Population (%)
>60
40-60
>18-40
>5-18
>3-5
>1-3
0-1
Age
Group
Population age-sex structure

33. Population Pyramid
This is bar graphs, one showing the number of
males, the other showing the number of females.
The bars represent age bands of 5 year-intervals.

34. Importance of studying population pyramids
1-Different shaped population pyramids indicate the stage of
development that a certain country has reached.
2-Population pyramids can indicate birth, mortality rates as
well as migration and wars.
For instance, a country whose pyramid has a wide base has
a high birth rate. If the numbers rapidly decrease, to from a
triangular shaped pyramid, then there must also be fairly high
death rates. Developed country with good health care, and
high life expectancy for example UK will have a relatively
narrow base, and there will be similar number of people in all
the bands up until the age of 70, when the numbers will start
to fall.

35. Mortality and migration can be represented by the slope
of the sides. The decrease in the width of strata of
different ages is brought about by deaths or migration.
The sharper the slope, as it goes upwards, the higher
are these reducing forces. Another type of event that
can be traced easily on the sides of population
pyramids, is the effect of war. Often this leads to large
imbalances in the population, with far more women
than men of fighting age remaining as the men have
been killed in battle

36. Developing countriesDeveloped countries
Wide (high BR)Narrow ( Low BR)Base
Sloping.
(high mortality)
Not sloping (Straight ).
(low mortality )
Side
Short
(Low life expectancy)
Tall
(high life expectancy).
Height
Narrow
(few people survive to old
age)
Wide
(large numbers of people >
60.
Apex
Low ( High births)High (low birth)Median Age
LowHighOld dependency
ratio
HighLowYoung dependency
ratio
Comparison between the Pyramids of developing & developed Countries

38. 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.

39. 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:

41. Dependency Ratio
• Ratio of those not economically productive to those
who are and it is defined in terms of age.
• high dependency ratio makes great strain on the
productive members of the population to provide for
the non-productive members
Pop: aged <15 + Pop: aged =>65
Dependency Ratio =
Pop aged between 15 and 64

42. 1. Young dependency : Presented by the surface area below the
horizontal line passing through 15 years of age.
Young dependency ratio
Population aged 0-15 years in a year & locality X 100
Population aged15-60 years ( same year & locality)
2-Old dependency: Presented by the surface area above the
horizontal line passing through 60 years of age
Old dependency ratio =
Population aged 60 Years and more in a year& locality X 100
Population aged15-60 years ( same year & locality)

43. 3-Total dependency: Presented by the surface area below the
horizontal line passing through 15 years of age and that
above the horizontal line passing through 60 years of age
Total dependency ratio:
Pop. aged <15 + pop. aged > 60 years in a year&localityX 100
Population aged15-60 years ( same year & locality)
Population pyramids can be used to help planning for the
future, as they can be used to project the percentages of
certain age groups in the population over the next 50
years.

44. Distribution of the population
The following questions need to be answered:
What is the percentage of inhabited land in relation to available land within the
national borders of a given country?
What is the population density/km2 for the inhabited area?
What is the population density/km2 for the available land?
What are the occurring population movements between different areas of the
country (e.g.: Urban - rural migration-).?
The answers to these questions are significant politically, economically and
socially
Changes in distribution are caused by the cumulative effects of fertility, mortality
external and internal migration.

45. Major demographic processes: Population
Dynamics
• Fertility
• Mortality
• Migration
I - Fertility (Natality)
Fertility is the actual reproductive performance of a woman or
a group of women. A woman's reproductive period is roughly
from 15 to 49 years of age.
• Fertility indicators
• Crude birth rate
• General fertility rate
• Age specific mortality rate
• Total fertility rate

46. Measures of Fertility
• Fertility = births in the population and factors
affection them
= measured in terms of actual birth
performance
= can be measured by relating the number of
birth to the size of population or a section of the
population
1. Crude Birth Rate (CBR)
2. General Fertility Rate (GFR)
3. Age Specific Fertility Rate (ASFR)

47. Crude Birth Rate
Number of live-births in a year
CBR = X 1000
Mid-year population of all ages
• simplest rate of fertility.
• the denominator “total population” is not the proper
population at risk, because it contains males and
females outside the reproductive age.
• CBR is much influenced by the composition of
population age and sex.

48. Factors affecting the crude birth rate:
Factors affecting the Live births
• Number of females specifically those 15-49 years
• The age of marriage
• Level of infant and preschool mortality rates
• Socioeconomic level of the country
• Economic value of children and lower expenses of rearing
children
• Cultural and religious factors
• Knowledge, attitudes and motives for adopting or rejecting
family planning
Factors affecting the mid year population
• Epidemics
• Wars
• Famine
• Migration

49. General Fertility Rate
Number of live-births in a year
GFR =
Females of reproductive age
in Mid-year population
• a better measure than CBR.
• reproductive age s/b clearly stated as (15-44) or
(15-49).
• births can occur outside the range but very few and
not affect the rate.
• although better than CBR, still affected by different
age composition

50. Age-specific fertility rate
Number of live-births
in a particular age group
GFR =
Females of particular age group
in Mid-year population
• usually calculated for 5 year age group.
• basic data required are;
- number of live-births by age of mother
- number of women in the population by age
group

51. Measures of Reproduction
1.Gross Reproduction Rate (GRR)
2.Net Reproduction Rate (NRR)
• Measures the effect of fertility over the period of
time
• Concerns with the degree of replacement
individuals of a given age in one generation by
another generation

52. 1. Gross Reproduction Rate
• Sum of age-specific fertility rates in year-interval over
the reproduction period for female live-birth only.
• Indicates the average number of daughters that would
be produce per women by a reproductive age group.
• Assuming non of those women died or migrated before
reaching the out of reproductive age
• GFR = 1 means “on the basic of current fertility, present
generation of women would reproduce itself exactly.
• The basic data needed are; number of female live-
births by age of mothers and the women population by
age.

53. 2. Net Reproduction Rate
• Similar to GRR except it allows to calculate the female
mortality

54. Types of migration
I- Internal migration
It is the movement within the boundaries of a given country.
1 - Rural - Urban migration.
2 - Movement of nomads.
3 - Movement of temporary and seasonal nature.
4 - Movement between and within urban areas.
II- External migration
a) Permanent migration: An example is the permanent
movement of to the U.S.A., Australia and Canada
b) Temporary migration: It is the migration over the
borders of one society to another for the aim of working for
a number of years, with the intent of an eventual return to
the motherland. An example is the migration of Egyptian
professionals and laborers to Arab Countries..
The role of migration role is minimal when compared to
fertility and mortality,

55. Population Growth
The population grows according to two factors: birth rate and
death rate. The difference between these two is called the rate of
natural increase.
The natural increase in size of any population is the product of
subtraction of deaths from births.
The rate of natural increase is expressed as a percent =
Rate of natural increase (RNI) =CBR – CDR
10
If the CBR is higher than the CDR ,the population will grow.
If the CBR is lower than the CDR , the population will fall.
If the CBR & CDR are there will be no natural increase.
The growth rate takes into consideration birth, death &migration.
Growth rate (GR) = RNI + Net migration rate
Net migration rate = Immigrants - emigrants
.

58. Health Statistics
• in many countries, declining death rates have
resulted in greater emphasis being placed on
morbidity measures.
• mortality data give no complete indication of the true
load of the sickness disability in a community.
• not all illnesses resulted in death problems in using
morbidity data have been d/t difficulty to define illness,
individuals differing in their perception of illness and
problems in diagnosis.

59. WHO Definition of Morbidity
• any departure, subjective or objective, from a state of
physiologic well-being.
• important units in morbidity data are;
- persons ill
- illness experienced (in terms of spells)
- duration of illness.
• common sources for morbidity data are; disease
notifications, hospital and clinic records, records of
different agencies, special registers on specific
diseases, and morbidity surveys.

60. Measures of Morbidity
1. Prevalence- Period prevalence
-Point prevalence
2. Incidence- Cumulative incidence
-Incidence density or incidence rate.
Prevalence measure describes the proportion of
population that is in the diseased state at a specific
time.
Incidence measure describe the rate of flow from the
disease free state to the diseased state.

61. Prevalence
Definition : Prevalence is the proportion of the
population that has the disease at a certain point in
time.
Number of people having the disease
at a specific time
P =
Number of individuals in the population
at that time

62. Incidence
Incident cases are newly occurring cases.
Cumulative incidence Rate
• is the proportion of individuals in disease free state
at the beginning of the period that move to the disease
state during the period.
Number of new cases in defined period
CI =
Number of disease-free people
at the beginning of defined period

63. Incidence rate( Incidence density)
The sum of the time periods in the denominator is
often measured in years and is referred to as
person-years.
I =
Numbers of new cases that occur during a defined
period of time
Sum of length of time for each individual in the
population is at risk of getting the disease

64. The magnitude of the disease prevalence depends on
Incidence and duration of the disease.
P = I*D
Prevalence
Incidence
Recovery Disability Death

65. Increased by;
• longer duration of disease
• prolongation of life of patient
without cure
• increase in new cases
• in-migration of cases
• in-migration of susceptible
people
• out-migration of healthy people
• improved diagnostic facilities

66. Decreased by;
• shorter duration of disease
• high fatality rate
• decrease in new cases
• in-migration of healthy people
• out-migration of cases
• improved cure rate of cases

67. Measures of Mortality
Crude Death Rate (CDR)
Number of deaths from all causes
in a year
CDR = X1000
Mid-year population of the same year
• represents the chance of dying for persons in the
population
• preliminary indication of the level or trend of mortality
prior to detail analysis
• valid for comparison of same area in different times

68. • Level of CDR is affected not only by the level of
mortality but also by the distribution of people of
differing mortality
• significant differences in CDR may arise entirely from
differences in the age-sex distribution of the population
Town A Town B
Age Pop: Dea: Rate Age Pop: Dea: Rate
0-15
16-30
31-45
46-60
>60
2000
1000
1000
2000
4000
40
10
10
60
200
2%
1%
1%
3%
5%
0-15
16-30
31-45
46-60
>60
1000
3000
4000
1000
1000
20
30
40
30
50
2%
1%
1%
3%
5%
Total 10000 320 3.2% Total 10000 170 1.7%

69. Age-specific Death Rate
Number of deaths from all causes
in a specific age group
ADR = X1000
Age-specific population in
mid-year population
• if age-specific death rates are further specified for
sex, it eliminates the differences d/t variations in
population composition
• such rates can be compared from one area to
another and from one period to another
• useful for NRR and life table

70. Standardized Death Rates
Direct Standardization
• Age-specific death rates of P1 and P2
• Total population and age stratum of Ps
P1 P2
Age
Stra-
tum
Pop
Count
ASD
Count
ASDR Pop
Count
ASD
Count
ASDR
0-1 Ps Known Ps Known
1-20 Ps Known Ps Known
20-40 Ps Known Ps Known
>40 Ps Known Ps Known
Total Ps Ps

71. Indirect Standardization
• Age-specific death rates of Ps
• Total population and age stratum of P1 and P2
P1 P2
Age
Stra-
tum
Pop
Count
ASD
Count
ASDR Pop
Count
ASD
Count
ASDR
0-1 Known Known Ps Known Known Ps
1-20 Known Known Ps Known Known Ps
20-40 Known Known Ps Known Known Ps
>40 Known Known Ps Known Known Ps
Total Known Known Known Known
SMR (P1) = O/E SMR (P2) = O/E

72. Infant Mortality Rate
Number of under one year deaths
IMR = X1000
Number of live-births
• one of the best indicators to assess the general
health status of a society
• useful for comparing the health status of the
population in the different communities or countries
• one of the criteria for PQLI

73. Causes of infant mortality
Neonatal Causes
(<1 month)
Post-neonatal Causes
(1-12 months)
•Immaturity
•Birth injuries and difficult
labor
•Congenital anomalies
•Hemolytic diseases of new
born
•Conditions of placenta and
cord
•Enteritis and other diarrhoeal
diseases
•Acute respiratory infections
•Enteritis and other diarrhoeal
diseases
•Acute respiratory infections
•Other CDs – pneumonia,
whooping cough, influenza
•Malnutrition
•Congenital anomalies
•Accidents

74. Neonatal Mortality Rate
Number of under one month deaths
NMR = X1000
Number of live-births
Post-neonatal Mortality Rate
Number of one to
twelve months deaths
PNMR = X1000
Number of live-births

75. Maternal Mortality Rate
Number of mother deaths
d/t pregnancy related causes
MMR = X1000
Number of live-births
• ideally the denominator should include all deliveries
and abortions
• good indicator for the health status of a society
• reflect the maternal and child health care services
and total social development

76. determinants of maternal mortality
Medical causes Social factors
Obstetric Causes
•Toxemia of pregnancy
•Hemorrhage
•Infections
•Obstructed labor
•Induced abortion
Non-obstetric Cuses
•Anemia
•Associated diseases, e.g.
cardiac, renal, metabolic
•Malignancy
•Accidents
•Age
•Parity
•Too closed pregnancies
•Family size
•Malnutrition
•Poverty
•Illiteracy
•Social customs
•Lack of maternity services
•Delivered by untrained BA
•Poor environ: sanitation
•Poor transportations

77. Perinatal Mortality Rate
Number of late fetal deaths
& early neonatal deaths
PNMR = X1000
Number of live-births
• late fetal death or stillbirth = fetal death after 28th
week of gestation (24th week recently)
• early neonatal period = under 1 week after birth
• late neonatal period = 1-4 weeks after birth

78. Under five mortality rate (U5MR)
• number of deaths of under five year children per
1000 live-births and more specifically, this is the
probability of dying between birth and exactly five
years of age
• U5MR can be calculated by 5 years prospective
study or summation of sequential age-specific death
rates for 5 consecutive years

79. Disease-specific Mortality Rate
Number of deaths
d/t specific disease
(*)MR = X1000
Mid-year population
Case Fatality Rate
Number of deaths
d/t specific disease
CFR = X100 (%)
Number of cases of
specific disease