3. Demography
• It involves the scientific study of the size, geographical distribution,
and composition of populations, and how these change over time
• Demographers are particularly interested in fertility (births),
mortality (deaths), and migration (territorial movements)
because these three variables are the components affecting
population change
3
5. Formal Demography and Population Studies
• Formal demography includes the collection and statistical analysis of
demographic data
• Population studies is more interdisciplinary and draws on the social
and biological sciences
5
15. Sources of Demographic Data
1) Population Censuses
2) Demographic Sample Surveys
3) Registration Systems
(a) Vital registration (births, deaths,…..)
(b) Population registers
(c) International migration statistics
4) Other
15
16.
17. Basic Demographic measures - Definitions
• Count Indicators - simply measure the number of events without a denominator
• Proportion Indicators - whose resultant values are typically expressed as a
percentage, are indicators for which the numerator is contained in the
denominator
• Percentage - Number or amount in each hundred
• Rates - measure the frequency of an event during a specified time, usually
expressed per 1,000 or 100,000 population, K. the rate is the basic measure of
disease occurrence
• Ratios - are indicators for which the numerator is not included in the
denominator
17
22. Sex Ratio
Sex Ratio at Birth
Sex ratio in Sri Lanka
1981 = 106 males in Sri Lanka
2001 = 97.9 males in Sri Lanka
3. Ratio
22
23. Ratio
• Ratio – A ratio is a single term including the relation size of two numbers. In other
words, it is a result of dividing the size of none of the two non-overlapping
groups processing some common characteristics by of the others.
23
Sex Ratio =
No. of Male Births
No. of Female births
X 100
* All events comes from one source, Ratios are indicators for which the
numerator is not included in the denominator
24. Sex Ratio - Sri Lanka
Year
Sex Ratio*
(Total Population)
Sex Ratio*
(Population 60+)
1946 113.0 119.5
1953 111.5 117.4
1963 108.2 126.0
1971 106.1 121.8
1981 104.0 112.9
2001 97.9 88.0
2011 96.6 82.5
2021 95.4 80.1
2031 94.4 77.9
2041 93.7 77.3
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* Number of males per 100 females
Note: During this period (1946-2001) sex ratio at birth has stayed virtually constant
between 103-104.
25. Proportion of urban population in
Sri Lanka
1981=23%
2001=18%
4. Proportion
25
27. Rates
• Rates – measure the frequency of an event during a specified time, usually
expressed per 1,000 or 100,000 population, K. the rate is the basic measure of
disease occurrence.
27
CBR =
No. of Births
Total mid year population
X 1000
* Sources are different and Numerator is included in the
Denominator
28. 5. Period Measures
Number of persons migrated to Colombo district between 1976-81
Infant mortality rate in Sri Lanka in 2018
6. Cohort Measures
Proportion of female persons attaining their 35th birthday in the year 2020
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29. Crude Birth Rate (CBR), Crude Death Rate (CDR), Maternal Mortality
Ratio (MMR) & Infant Mortality Rate (IMR)
29
CBR =
No. of Births
Total mid year population
X 1000
CDR =
No. of Deaths
Total mid year population
X 1000
IMR =
No. of Deaths of infants under I years of age
Total Live Births X 1000
MMR =
No. of Maternal deaths
Total Live Births
X 100,000
30.
31.
32. Child Mortality Rate (CMR), Cause Specific Death Rate (CSDR), General Fertility Rate
(GFR) &
Age Specific fertility Rate (IMR)
32
CSDR =
No. of Deaths per specific cause
Total Population
X K
ASFR =
No. of live Births to woman in a given age
No. of woman in the same age group
X 1000
CMR =
No. of Child Deaths, (1-4) years of age
Total population in that age group
X 1000
GFR =
No. of live Births
No of woman aged 15 - 49
X 1000
33. Case Rate (CR), Case Fatality Rate (CFR),
Still Birth Rate & Low Birth Weight Rate
33
CFR =
No. of persons dying from the diseases
No. of persons developing the diseases
X 1000
Still Birth Rate =
Still Births (28 weeks of gestation)
No of births+ Still Births
X 1000
X K
CR =
No. of reported cases of a disease during a given
year
Total population
X 1000
Low birth
Weight Rate
# of live births less than 2500 grams.
No of live births
X 1000
=
34. Sex Ratio, Dependency Ratio, Child-Woman Ratio &
Cause Specific Death Ratio
34
Dependency Ratio =
Population (under 15 + over 64 years)
Population aged 15 - 64
X 100
Child Woman Ratio =
No of children under 15 years old
Woman aged 15 - 49
X 1000
Cause Specific Death Ratio =
Deaths due to specific cause
Total deaths
X K
Sex Ratio =
Male Population
X 100
Female population
35. Statistical Definitions
• Live birth – The complete expulsion or extraction from its mother of a
product of conception, irrespective of the duration of the pregnancy,
which, after such separation, breathes or shows any other evidence of life,
such as beating of the heart, pulsation of the umbilical cord, or definite
movement of voluntary muscles, weather or not the umbilical cord has
been cut or the placenta is attached; each product of such a birth is
considered live born.
• Neonatal death – the neonatal period commences at birth and end 28
completed days after birth.
• Early Neonatal deaths – deaths during first seven days of life
• Late Neonatal deaths – deaths after 7 day but before 28 days of life
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36. Information Generation – vital statistics PHM
• Eligible Family Register
• Birth and Immunization Register
• Pregnant Mothers Register
• Expected Dates Register
• Family Planning Register
Registers
Records
• Pregnancy Records
• Child Health Development Record
• Family Planning Field Record
• Daily Statement of work
Returns
• PHMs Monthly statement
• Family Planning Monthly Return
37.
38. Why we need information?
• Need assessment.
• Situational analysis
• Trend assessment
• Disease incidence
• Disease prevalence
• Surveillance
• Forecasting
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39. Why we need information?
• Development planning
• Monitoring
• Evaluation
• Policy decision
• Resource allocation
• Education
• Research ect..
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