This document provides information about key concepts and indicators used in demography and epidemiology. It defines demography as the study of populations and their size, structure and changes over time. Key components of demography include fertility, mortality, migration and population growth. Several population indicators and rates are described such as crude birth rate, general fertility rate, total fertility rate, crude death rate, infant mortality rate, and life expectancy. Methods for measuring disability, natality, and migration are also summarized.

1. Dr.S.Kalpana
Dept of Epidemiology
TNMGRMU

2. • 1. DEMOS - People.
• 2. GRAPHO - To write.
• The word was coined by JOHN GRUNT

3. Demography—The study of a population
in its static and dynamic aspects

4. Demography is the branch of social
size, structure, which deals with
the study of size, structure and
distribution of populations, along
with the spatial and temporal
changes in them in response to
birth, migration, ageing and death.

5. • Demography is the science of population. In
it's most general meaning, a population is a
set of people who live in a specific land area
: a commune, a district, a country or a
continent,etc.
• A formal demography is concerned with the
size, distribution, structure and changes of
population

6. DEMOGRAPHY
CYCLE
HIGH STATIONARY.
EARLY EXPANDING.
LATE EXPANDING.
LOW STATIONARY.
DECLINING.

7. HIGH STATIONARY.
EARLY EXPANDING.
LATE EXPANDING.
LOW STATIONARY.
DECLINING.
High Birth Rate
High Death Rate
Unchanged Birth Rate
Decline Death Rate
Fall in Birth Rate
Death Rate further
Low Birth Rate
Low Death Rate
Birth rate lower than
Death Rate

8. Static aspects include characteristics at a
point in time such as composition by:
– Age
– Sex
– Race
– Marital status
– Economic characteristics

9. • 1. Measurement of Mortality.
• 2. Measurement of Morbidity.
• 3. Measurement of disability.
• 4. Measurement of natality.
• 5. Measurement of the presence,
absence or distribution of the
characteristics or attributes of the
disease.

10. Dynamic aspects are:
– Fertility
– Mortality
– Nuptiality
– Migration
– Growth

11. 1
Demographic Analysis — The study of
components of variation and change in
demographic variables and the
relationships between them
This is also called formal demography
or demographic methods

12. 1
Population Studies—The study of the
relationships between demographic
variables and other variables such as social
and economic variables

13. An epidemiologist usually expresses
the health event as RATES, RATIOS
or PROPOTION.

14. • A rate measures the occurrence of
some particular event in a
population during a given period of
time period.
• It is the statement of the risk of of
developing a condition.

15. It indicates the change in some event
that takes place in a population over a
period of time.
DEATH RATE = NUMBER OF DEATHS
MID YEAR POP
X 1000

16. Weekly death rate = Deaths in a week x 52
Mid year population
x 1000

17. • A rate comprises the following
elements.
1. Numerator.
2. Denominator.
3. Multiplier.

18. The time dimension is usually a
calender year.
The rate is expresses per
1000 or some round
figure.(selected according to
convenience or convention to
avoid fraction).

19. • Ratio expresses a relation in
size between two random
quantities.
E.g., x : y (or) x/y.

20. • The numerator is not a component
of the denominator.
• The numerator and denominator
may involve an interval of time or
may be simultaneous in time.
The number of children with scabies at a certain
time.
The number of children with malnutrition at a
certain time

21. • 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.

22. The number of children with scabies
at a certain time.
x 100
The total number of children in the
village at the same time

23. • Mortality refers to the number of
deaths in a given time or a place
or a proportion odf deaths in
relation to a population.
• E.g., : 1. Crude Death Rate.
2. Infant Mortality Rate.
3. Maternal Mortality Rate
4. Life Expectancy.

24. • It refers to diseases and illness, injuries
and disabilities in a population.
• Data on the frequency and distribution of a
disease helps in controlling its spread, and
in some cases it may lead to the
identification of cases.

25. Case Rate :
The case rate is the number of reported
cases of a specific disease or illness
per 100,000 population during a given
year.

26. Case Fatality Rate : The Case
Fatality Rate is the proportion
of persons contacting a
disease who die of that disease
during a specified time
period.

27. • Dependancy Ratio : The ratio of the
economically dependent part of the
population to the productive part; arbitrarily
defined as the ratio of the elderly ( ages 65
and older) plus the young (under age 15) to
the population in the "working ages".

28. • Natality in population ecology is
the scientific term for Birth Rate.
• Along with mortality rate,
natality rate is used to calculate
the dynamics of a population.

29. • They are the key factors in determining
whether a population is increasing,
decreasing or staying the same in size.
• Natality is the greatest influence on a
population’s increase.

30. • Natality is shown as a crude birth rate or specific
birth rate.
• Crude Birth Rate is used when calculating
population size (number of births per 1000
population/year).
• whereas Specific Birth Rate is used relative to
a specific criterion such as age.
• By calculating specific birth rate, the results are
seen in an age-specific schedule of births.

32. NUMBER IF LIVE BIRTHS DURING
THE YEAR.
ESTIMATED MID YEAR
POPULATION
X 1000BIRTH RATE =

33. NUMBER OF LIVE BIRTHS
DURING A YEAR.
MID YEAR FEMALE POP (15-49)
IN THE SAME YEAR
X 1000GFR =

34. NUMBER OF LIVE
BIRTHS DURING A
YEAR.
MID YEAR MARRIED FEMALE
POP (15-49) YRS
GMFR = X 1000

35. NUMBER OF LIVE BIRTHS IN A
PARTICULAR AGE GROUP.
MID YEAR POP OF THE
SAME AGE GROUP
ASFR = X 1000

36. NUMBER OF LIVE BIRTHS IN A
PARTICULAR AGE GROUP.
MID YAER POP OF THE SAME AGE
GROUP.
ASMFR = X 1000

37. • It is the average number of children a
women can give birth throughout the
reproductive period.
• It is represented by summing the age
specific fertility rates for all ages; if 5 - year
age groups are used, the sum of the rates is
multiplied by 5.

38. 45 - 49
15 - 19
1000
TFR =
5 X ∑ ASFR

39. Average number of children that would be
born to a married women if she experiences
the current fertility pattern through her
reproductive span.

40. 45 - 49
15 -19
1000
5 X ∑ ASMFRTMFR =

41. Average number of girls that would be
borne to a women if she experiences
the curent fertility pattern throught her
reproductive span (15 - 49 years)
having no mortality.

42. • NRR is defined as the number of daughters a
new borne girl will bear during her lifetime
assuming fixed age-specific fertility and
mortality rates.

43. • If NRR is < 1, then the reproductive
performance of the population is
said to be below replacement
level.

44. • The marriage rate (CRUDE MARRIAGE
RATE) is the number of marriages per 1000
total population in a given year.

45. NUMBER OF MARRIAGES IN
THE YEAR
MID YEAR POPULATION
MR = X 1000

46. • Is the number of children 0 -
4 yrs of age per 1000 women
of child bearing age.

47. • It is the ratio of number of
pregnancies in a year to married
women in the ages 15-49 yrs.
• The "number of pregnancies"
includes all pregnancies, whether
or had terminated as live births,
stillbirths or abortions or had not
yet terminated.

48. • The annual number of all
types of abortions, usually
per 1000 women of child
bearing age (15-19 yrs).

49. • This is calculated by dividing
the number of abortions
performed during a
particular timeperiod by
the number of live births
over the same
period.

50. NUMBER OF DEATHS DURING A
YEAR
X 1000
MID YEAR POPULATION
CDR =

51. NUMBER OF DEATHS FROM TB DURING A
CALENDER YEAR.
MID YEAR POPULATION
SDR = X 1000

52. NUMBER OF DEATHS OF
PERSONS AGED 15-20
DURING A CALENDER
MID YEAR POPULATION OF
PERSONS AGED 15-20
SPECIFIC DEATH
RATE (15-20 YRS) = YEAR. X 1000

53. TOTAL NUMBER OF DEATHS
DUE TO A PARTICULAR
DISEASE
CFR = X 100
TOTAL NUMBER OF CASES
DUE TO THE SAME DISEASE

54. NUMBER OF DEATHS
FROM THE SPECIFIC
DISEASE IN A YEAR
TOTAL DEATHS FROM
ALL CAUSES IN THAT
YEAR
X 100PMR =

55. TOTAL NUMBER OF PATIENTS
ALIVE AFTER 5 YEARS
TOTAL NUMBER OF PATIENTS
DIAGNOSED OR TREATED
SURVIVAL
RATE = X 100

56. OBSERVED DEATHS
EXPECTED DEATHS
SMR = X 100

57. NUMBER OF DEATHS OF
CHILDREN LESS THAN 1
YEAR OF AGE IN A YEAR
NUMBER OF LIVE BIRTHS
IN THE SAME YEAR
X 1000IMR =

58. NUMBER OF NEW CASES OF
A SPECIFIED DISEASE
DURING A SPECIFIED TIME
INTERVAL
TOTAL POPULATION AT RISK
DURING THE SAME
INTERVAL
X 100AR =

59. FOETAL DEATHS WEIGHING
OVER 1000g AT BIRTH
DURING THE YEAR
TOTAL LIVE + STILL BIRTHS
WEIGHING OVER 1000g AT
BIRTH DURING THE YEAR
X 1000SBR =

60. LATE FOETAL AND EARLY
NEO NATAL DEATHS
WEIGHING OVER 1000g
AT BIRTH
TOTAL LIVE BIRTHS
WEIGHING OVER 1000g
AT BIRTH
X 1000PMR =

61. NUMBER OF DEATHS
OF CHILDREN
UNDER 28 DAYS OF
AGE IN A YEAR
TOTAL LIVE BIRTHS IN
THE SAME YEAR
X 1000NMR =

62. NUMBER OF DEATHS OF
CHILDREN BETWEEN 28
DAYS AND ONE YEAR OF
AGE IN A GIVEN YEAR
TOTAL LIVE BIRTHS IN THE
SAME YEAR
X 1000PNMR =

63. NUMBER OF DEATHS OF
CHILDREN AGED 1-4
YEARS DURING A YEAR
TOTAL NUMBER OF
CHILDREN AGED 1-4
YEARS AT THE MIDDLE
OF THE YEAR
X 1000CDR =

64. NUMBER OF DEATHS OF
CHILDREN LESS THAN 5
YEARS OF AGE IN A
GIVEN YEAR
NUMBER OF LIVE BIRTHS
IN THE SAME YEAR
X 1000CMR =

65. 1000 - UNDER 5
MORTALITY RATE
10

66. TOTAL NUMBER OF FEMALE DEATHS DUE TO COMPLICATIONS
OF PREGNANCY, CHILDBIRTH OR WITHIN 42 DAYS OF
DELIVERY FROM PUERPERAL CAUSES IN AN AREA
DURING A GIVEN YEAR
TOTAL NUMBER OF LIVE BIRTHS IN THE SAME AREA
AND YEAR
X 1000 /
100000
MMR =

67. INDICATORS USED TO MEASURE DISABILITY :
1. SULLIVAN INDEX
2. HEALTH ADJUSTED LIFE EXPECTANCY (HALE).
3. DISABILITY ADJUSTED LIFE YEAR

68. SULLIVAN INDEX
LIFE EXPECTANCY - (PROBABLE DURATION
OF BED DISABILITY + INABILITY TO
PERFORM MAJOR ACTIVITIES)

69. • Is an indicator of health which
measures healthy life expectancy.
• HALE is equivalent to the number
of years newborn child expected
to live with full health.

70. • Is used to express the years of
life lost to premature death and
years lived with disability for
severity of disability.
• ONE DALY = ONE LOST YEAR OF
HEALTHY LIFE

71. Number of reported cases of
a specific disease or illness
100,000 population during a
given year

72. NUMBER OF EMIGRANTS DEPARTING
AN AREA OF ORIGIN
1000 POPULATION AT THAT AREA OF
ORIGIN IN A GIVEN YEAR

73. The net effect of immigration and
emigration on an area's population
(increase or decrease) is refered to as
net migration.
The net migration shows the net effect
of immigration & emigration on an
area's population of the area in a given
year.

74. The growth rate is the rate at which a
population is increasing (or
decreasing) in a given year due to
natural increase and net migration,
expressed as a percentage of the base
population.
•The growth rate takes in to account
all components of population growth:
births, deaths and migration.

75. The number of years which an
individual at a given age could
expect to live, at present
mortality levels

76. • Analysis patterns and trends related to human religion,
nationality, education and ethnicity.
• Estimates are reliable standards for judging the accuracy of
the census information gathered at any time.
• Estimates size and flow of populations of workers; in
population ecology, the focus is on birth, death and movement
of firms and institutional forms.
• Uses administrative records to develop an independent
estimate of the population.

77. • Provides insight into the links between these
characteristics and cultural, economic, geographic
and other social attributes present in a given area.
• Demographic analysis is a powerful tool that can
explain a number of sociological phenomena.

78. All live-born infants should be
registered and counted as such
irrespective of gestational age or
whether alive or dead at time of
registration, and if they die at any
time following birth they should also
be registered and counted as deaths

79. The United Nations recommends that
the following be collected at a
minimum for live birth registration:
– Data on event
•Date of occurrence
•Date of registration
•Place of occurrence
•Type of birth/delivery
•Attendance at birth

80. Data on infant:
– Sex
– Legitimacy status
– Weight at birth

81. 81
Data on mother:
– Age or date of birth
– Number of previous children born alive
– Date of marriage or duration of
marriage
– Place of usual residence

82. Death—Permanent disappearance of
all evidence of life at any time after
live birth has taken place (post-natal
cessation of vital functions without
capability of resuscitation)
This definition excludes fetal deaths

83. 83
Fetal Death—Death prior to the
complete expulsion or extraction from
its mother of a product of conception,
irrespective of the duration of
pregnancy

84.  Three major categories of fetal deaths
recommended by WHO:
– Early fetal death: < 20 completed weeks of
gestation
– Intermediate fetal death:  20 but  28
weeks
– Late fetal death:  28 weeks

85. Stillbirth—Late fetal death
To be used only if essential for national
purposes

86.  The following be collected at the minimum for
death registration
– Data on event:
• Date of occurrence
• Date of registration
• Place of occurrence
• Cause of death
• Certifier

87.  Data on decedent:
– Age or date of birth
– Sex
– Marital status
– Occupation
– Place of usual residence

88.  Knowledge of certifier
 Certifier may never see deceased
 “Garbage codes”: missing, senility, etc . . .
 Heart versus brain function loss in the definition of
death

89.  Bleeding
 Burnt and scalded
 Drowned
 Excessive drinking
 Frightened
 Grief
 Hanging
 Killed by several
accidents
 Murdered
 Poisoned
 Smothered
 Shot
 Starved
 Vomiting

90.  Note: causes of death can be regrouped in smaller
categories than in ICD
– e.g., Preston’s classification of causes of death in 12
categories

91.  Marriage—Ceremony or process by which the legal
relationship of husband and wife is constituted
 The legality of the union may be established by civil,
religious, or other means as recognized by the laws of each
country

92.  The following be collected at a minimum for marriage
registration:
– Data on event
• Date of occurrence
• Date of registration
• Place of occurrence
• Type of marriage—civil, religious, customary

93. 34
 Data on bride and groom
– Age or date of birth
– Previous marital status
– Place of usual residence

94.  Divorce—Final legal dissolution of a marriage, that is,
that separation of husband and wife which confers
on the parties the right to remarriage under civil,
religious and/or other provisions, according to the
laws of each country

95.  Demography is the study of a population in its
static and dynamic aspects
 Civil registration is a system developed to collect
data on vital events (live births, deaths,
marriages and divorces) happening to a
population

96.  Civil registration is continuous and universal (it
should give small area data)
 There are advantages and disadvantages to the
system and its completeness varies widely
between countries and continents

97. Censuses

98. Census—The total process of collecting, compiling,
analyzing, and publishing or otherwise disseminating
demographic, economic, and social data pertaining to all
persons in a country or in a well-delineated part of a
country at a specified time

99. 99
Universality
Simultaneity
Individual enumeration

100. A census contains:
– Demographic data (at least age and
sex)
– Economic data (e.g., occupation and
income)
– Social (e.g., education and housing)

101. 100-percent component
– Household relationship
– Sex
– Race
– Age
– Marital status
– Hispanic origin

102. Sample component
Social characteristics
– Education (enrollment and attainment)
– Place of birth, citizenship, and year of
entry into the United States

103. Social characteristics
– Ancestry
– Language spoken at home
– Migration
– Disability
– Fertility
– Veteran status

104. Economic characteristics
– Labor force
– Occupation, industry, and class of
worker
– Place of work and journey to work
– Work experience
– Income
– Year last worked

105. A census can be conducted:
– Legal or customary attachment to an
area (you are registered where you
usually reside)
– Physical residence (you are registered
where you are currently
staying/residing at the time of the
census)

106.  Establish administrative tree (census officers,
supervisors, enumerators)
 Develop questionnaire(s)
 Cartography
 Define enumeration areas
 Pretest enumeration processes
 Design data processing system
 Enumeration (postal with follow-up, general
canvas)

107. Estimation of undercounts
– Post-enumeration survey
– Demographic evaluation

108. Net Population Undercount (In Millions)
In The Census By Demographic Analysis, 1980-2020
Race 1980 2000 2020
Total
Population
Undercount Numbers
Non-blacks
Population
Undercount Numbers
Blacks
Population
Undercount Numbers

109.  Universal, hence small area data available
 National effort
 Provides frame for later sample surveys
 Provides population denominators

110. Size limits content and quality control
efforts
Cost limits frequency
Delay between field work and results

111.  Population definition
 Coverage change between censuses
 Treatment of non-response

112.  Censuses are universal, simultaneous and
require individual enumeration
 A census can be conducted de jure, de facto
or some combination
 Preparing a census is a meticulous process
including many steps
 Censuses should give small area data, although
coverage is not always certain

113.  The cost is high, but not having the
information may be more costly
 Censuses should be evaluated to estimate the
quality of the data; several techniques exist for
that purpose
 There are advantages and disadvantages to
the system

114. Surveys

115.  Purpose
– Obtain information from a sample
representative of some population
 Content
– Varies widely
– e.g., fertility, child mortality, migration

116.  Representative sample of some population
 Smaller size than census allows collection of
more in-depth information that can then be
generalized

117.  Single-round retrospective
– Census-type household surveys
– Focused, (e.g., Contraceptive Prevalence
Survey (CPS))
– Birth/Maternity history (World Fertility
Survey (WFS), Demographic and Health
Survey (DHS))
– Health monitoring

118. 118
Multi-round follow-up (prospective)

119.  Sampling frame, generally from census
 Separate strata are often defined for sampling
– The provinces of a country could be strata or
urban and rural areas
– There may be multiple strata

120.  Census enumeration areas or sections of them
may constitute a cluster from which households
are sampled (clusters are typically sampled
within strata and then households within
clusters)
 Sample size may range from one to four
thousand women to hundreds of thousands of
people
 Sampled clusters may range from 20 to 400 or
more

121.  Single-round retrospective
– Can be quick
– Relatively inexpensive
– Flexible
– Can include detailed data
– Needs little continuity effort

122.  Multi-round prospective
– Some control on coverage and content
errors
– Follow-up allows control for sampling
distortion

123. 123
 Single-round retrospective
– Coverage and content errors
– Misses certain types of events
 Multi-round prospective
– Slow
– Needs continuity of effort over
(extended) time
– High cost

124.  Surveys are done to obtain information from a
sample representative of some population
 Surveys are of a smaller size than a census,
which allows for collection of more in-depth
information that can then be generalized
 There are many types of surveys

125.  The sampling method used in surveys is often
multistage (e.g., household within cluster,
themselves taken within strata)
 Surveys are less expensive than censuses and
civil registration (smaller size allows for quick
collection of more in-depth information than any
of the other two systems)
 They have advantages and disadvantages