UNIT 1 POPULATION DYNAMICS
AND EPIDEMIOLOGY
I Structure
i
'
! 1.1 Introduction
I 1.2 Role of Vital Statistics in Public Health
I
I
1.3 Vital Statistics in Asian Countries
1.4 Sources of Data on Vital Statistics
i 1.5 Fertility Measures and Determinants
1 1.6
1.7
Epidemiological Methods: Morbidity, Mortality and their Determinants
Other Population Parameters
I\ 1.8 Let US Sum u p
1.9 Glossary
1.10 Answers to Check Your Progress Exercises
I \ 1.1 INTRODUCTION
Research conducted s o far in the field of population parameters has given us
scientific evidence regarding the influence of these factors on nutritional status
of the population in general. In addition, the experiences in developing
' programmes generated ideas about the inter-relationship between population
parameters and nutritional status of people. In the light of these evidences you
may be aware about some of these implications. This unit gives you more
details. In this context, focussed efforts are being made here to familiarise you
with important vital events such as marriages (nuptiality), births (fertility),
diseases (morbidity), deaths (mortality), and their levels, trends and
determinants. As you go through this unit, you would realise that these vital
Istatistics are of crucial importance in planning for public health and improving
he quality of life of people.
hc various fertility and mortality rates important from the point of view of
ublic health which are discussed as part of this unit will help to acquaint you
the method 6f computation, importance of the vital rates as well as
~ d t e going
r through this unit, you should be able to :
describe the levels and trends of various population parameters in India and
other Asian countries and at regional levels;
compute major rates and ratios related to marriages, births, deaths, growth
and other vital events;
-
identify major determinants and patterns of vital events, and
explain the prevalence and control of major diseases.
,Health Indicators
1.2 ROLE OF VITAL STATISTICS IN PUBLIC
HEALTH
How do you think vital statistics can be of help for a community/country:~
There are many ways in which vital statistics can be of use. In fact, vital rates
help to monitor the overall socio-economic development of a community1
country. Fertil'ity and mortality in a community are indicators of overall health
and nutrition (i.e. quality of life) of a community and hence show the need for
socio-economic development.
' Analysis
of vital statistics helps the Government {policy and programme
planners) to plan for health services for reaching the general population and
improving health related socio-economic conditions. One can set objectives for
achieving targets (like reducing mortality among children, reducing maternal
deaths during child birth etc.) and vital rateslstatistics can help in finding out
whether targets are achieved or not.
Another reason for collecting vital statistics is that it helps to compare the
health and nutritional status of people of two communities/countries and also
the same community/country over a period of time. Thus, knowledge on
various vital events during different five year plan periods and census decades
will help programme managers, planners and administrators to know the impact
of developmental programmes particularly their successes over time.
1.3 VITAL STATISTICS IN ASIAN COUNTRIES
,
Most vital statistics are expressed as vital rates. Let us define this term. When i
the vital statistics of fertility/morbidity/mortalityare expressed as number of I
I
people with a state of illness or number of events (e.g. birthsldeaths) in
relation to total population at risk (group ofpeople having certain similar
characteristics like age, sex region etc.) is termed as vital rates. This definition 'I
of vital rates may seem a little difficult to you, when you read it for the first
time. However, by carefully glancing at it again, you will surely be able to
understand it.
Although India was more or less similar in developmental aspects with many
Asian Countries, vital statistics varied among these countries. How did it
happen? It might be due to differential progress achieved by Asian countries
through differential emphasis given to one or the other priority areas of
development in the recent past. For instance, certain countries and regions have
given highest priority for education, health, family planning and infrastructural
* - Q
development. But certain other countries have given highest importance to
industrialisation and/or agricultural development neglecting social
development. In this context, China, Thailand, South Korea, Malaysia,
Sri Lanka have made good progress in planning and infrastructure .
Consequently, they attained rapid modernisation and improvement in quality
of life of the population. On the other hand, the Government of India gave
highest priority for industrialisation and agriculture, neglecting the social ,
development. We have just mentioned these differential models of development
which have contributed to differences in several vital events. While many of
the progressive Asian countries rapidly brought down their mortality and
morbidity rates, India is lagging behind very much.
, CBR IMR CDR Female Female
Crude Infant Crude Life mean age
birth rate mortality rate death rate expectancy at marriage
(1992) (1992) (1992) (1992) (1991)
China 20.3 28 6.5 72.4 23.0
South Korea 16.4 12 5.8 73.6 24.7
Sri Lanka 20.9 25 5.9 73.6 24.4
India 29.9 92 11.0 58.0 18.7
Source : Population Reference Bureau 1993 World Population Data sheet, PRB,
Washington.
Let us now find out how this information regarding vital rates is collected and
processed.
The main sources of data on vital statistics are :
1) Census
2) Population Registers
3) Sample Registration Scheme
4) National Sample Surveys
5) Health Services Records
6) Special Surveys
7) Disease Registers
Before learning more details about each of these sources, you should
remember that each of these sources have their own limitations and a country
cannot solely depend on a single source. Usually information from various
I
sources is compiled together to get vital statistics.
Census
Let us first define the meaning of the term "Census". Census means complete
counting of all individuals/houses (individuals-population-Census; houses-
- .
etc. of the population. The first census in our country took place in 1872 and
subsequently it is being conducted once in ten years. In India the latest census
was held on 1st March 1991.
population census provides useful basic information for calculating vital rates.
Similarly, housing census helps to analyse environmental conditions (such as
water supply, toilet facilities, availability of space per person, etc.).
, Health lndlcators Population Registers
h~some countries, such as Sweden, Finland, Belgium, Israel, Taiwan and
Korea, data about population can be obtained from continuously maintained
population registers, in which the name of each person in the country is
entered. Important migratory movements of individuals are also registered. The
primary objective of setting up this system of population registers is to
establish the identity of individuals and control them. The registers, however,
are also used to obtain such demographic information as current population
size, internal migration, data on vital events, etc.
Sample Registration Scheme
As you know, in every community records of births, deaths and marriages are
kept by either the local authorities or by religious'leaders. If these records are
complete and kept systematically, they can be used for estimation of fertility,
mortality and marriage rates.
However, there is one limitation. In our country these records are usually not
complete. This is because of ignorance, illiteracy, indifference and poor
systems of management. There is no incentive also to register deaths, births
and marriages. Hence, people usually do not report these vital events promptly.
Inspite of this, systematic analysis of these records do help to provide vital
statistics of some public health significance.
National Sample Survey
The main objective of the National Sample Survey has been to collect data on
some important socio-economic aspects on a comprehensive basis for the whole
country through its various rounds by using the technique of sample survey. .
The First Round of the National Sample Survey (NSS) was conducted in 1950;
since then, information on different items has been collected through various
rounds of the NSS. The topics covered so far include the following: fertility,
mortality, population growth, economically active population, family planning,
/
employment and unemployment, consumers, expenditure patterns, housing
conditions, manufacturing industries, physically handicapped persons.
Health Service Records
Information can also,be obtained from health service records kept by the health
sector for administrative purposes (e.g. maternal mortality in hospitals, disease
specific morbidity, information about birth weight, height during infancy and
childhood arm circumference of children, information on immunization and
prevention and control of certain endemic diseases).
Though health service records provide useful data for vital statistics, they have
their limitations unless kept properly. Their limitation is that they are kept for
administrative purposes rather than monitoring purposes and that too only at
places where health services are utilised.
Special Surveys
Household surveys undertaken by the members of a community, village agents,
local officials or researchers are very useful in providing information on age- .
specific and disease-specific mortality. These (when carried out at the national
level) are more frequently used for providing information for vital statistics1
rates.
Disease Registers
Disease registers maintained by various hospitals provide data on mortality and
morbidity for selected specific diseases and the treatment given.
8
AND EPIDEMIOLOGY
I Structure
i
'
! 1.1 Introduction
I 1.2 Role of Vital Statistics in Public Health
I
I
1.3 Vital Statistics in Asian Countries
1.4 Sources of Data on Vital Statistics
i 1.5 Fertility Measures and Determinants
1 1.6
1.7
Epidemiological Methods: Morbidity, Mortality and their Determinants
Other Population Parameters
I\ 1.8 Let US Sum u p
1.9 Glossary
1.10 Answers to Check Your Progress Exercises
I \ 1.1 INTRODUCTION
Research conducted s o far in the field of population parameters has given us
scientific evidence regarding the influence of these factors on nutritional status
of the population in general. In addition, the experiences in developing
' programmes generated ideas about the inter-relationship between population
parameters and nutritional status of people. In the light of these evidences you
may be aware about some of these implications. This unit gives you more
details. In this context, focussed efforts are being made here to familiarise you
with important vital events such as marriages (nuptiality), births (fertility),
diseases (morbidity), deaths (mortality), and their levels, trends and
determinants. As you go through this unit, you would realise that these vital
Istatistics are of crucial importance in planning for public health and improving
he quality of life of people.
hc various fertility and mortality rates important from the point of view of
ublic health which are discussed as part of this unit will help to acquaint you
the method 6f computation, importance of the vital rates as well as
~ d t e going
r through this unit, you should be able to :
describe the levels and trends of various population parameters in India and
other Asian countries and at regional levels;
compute major rates and ratios related to marriages, births, deaths, growth
and other vital events;
-
identify major determinants and patterns of vital events, and
explain the prevalence and control of major diseases.
,Health Indicators
1.2 ROLE OF VITAL STATISTICS IN PUBLIC
HEALTH
How do you think vital statistics can be of help for a community/country:~
There are many ways in which vital statistics can be of use. In fact, vital rates
help to monitor the overall socio-economic development of a community1
country. Fertil'ity and mortality in a community are indicators of overall health
and nutrition (i.e. quality of life) of a community and hence show the need for
socio-economic development.
' Analysis
of vital statistics helps the Government {policy and programme
planners) to plan for health services for reaching the general population and
improving health related socio-economic conditions. One can set objectives for
achieving targets (like reducing mortality among children, reducing maternal
deaths during child birth etc.) and vital rateslstatistics can help in finding out
whether targets are achieved or not.
Another reason for collecting vital statistics is that it helps to compare the
health and nutritional status of people of two communities/countries and also
the same community/country over a period of time. Thus, knowledge on
various vital events during different five year plan periods and census decades
will help programme managers, planners and administrators to know the impact
of developmental programmes particularly their successes over time.
1.3 VITAL STATISTICS IN ASIAN COUNTRIES
,
Most vital statistics are expressed as vital rates. Let us define this term. When i
the vital statistics of fertility/morbidity/mortalityare expressed as number of I
I
people with a state of illness or number of events (e.g. birthsldeaths) in
relation to total population at risk (group ofpeople having certain similar
characteristics like age, sex region etc.) is termed as vital rates. This definition 'I
of vital rates may seem a little difficult to you, when you read it for the first
time. However, by carefully glancing at it again, you will surely be able to
understand it.
Although India was more or less similar in developmental aspects with many
Asian Countries, vital statistics varied among these countries. How did it
happen? It might be due to differential progress achieved by Asian countries
through differential emphasis given to one or the other priority areas of
development in the recent past. For instance, certain countries and regions have
given highest priority for education, health, family planning and infrastructural
* - Q
development. But certain other countries have given highest importance to
industrialisation and/or agricultural development neglecting social
development. In this context, China, Thailand, South Korea, Malaysia,
Sri Lanka have made good progress in planning and infrastructure .
Consequently, they attained rapid modernisation and improvement in quality
of life of the population. On the other hand, the Government of India gave
highest priority for industrialisation and agriculture, neglecting the social ,
development. We have just mentioned these differential models of development
which have contributed to differences in several vital events. While many of
the progressive Asian countries rapidly brought down their mortality and
morbidity rates, India is lagging behind very much.
, CBR IMR CDR Female Female
Crude Infant Crude Life mean age
birth rate mortality rate death rate expectancy at marriage
(1992) (1992) (1992) (1992) (1991)
China 20.3 28 6.5 72.4 23.0
South Korea 16.4 12 5.8 73.6 24.7
Sri Lanka 20.9 25 5.9 73.6 24.4
India 29.9 92 11.0 58.0 18.7
Source : Population Reference Bureau 1993 World Population Data sheet, PRB,
Washington.
Let us now find out how this information regarding vital rates is collected and
processed.
The main sources of data on vital statistics are :
1) Census
2) Population Registers
3) Sample Registration Scheme
4) National Sample Surveys
5) Health Services Records
6) Special Surveys
7) Disease Registers
Before learning more details about each of these sources, you should
remember that each of these sources have their own limitations and a country
cannot solely depend on a single source. Usually information from various
I
sources is compiled together to get vital statistics.
Census
Let us first define the meaning of the term "Census". Census means complete
counting of all individuals/houses (individuals-population-Census; houses-
- .
etc. of the population. The first census in our country took place in 1872 and
subsequently it is being conducted once in ten years. In India the latest census
was held on 1st March 1991.
population census provides useful basic information for calculating vital rates.
Similarly, housing census helps to analyse environmental conditions (such as
water supply, toilet facilities, availability of space per person, etc.).
, Health lndlcators Population Registers
h~some countries, such as Sweden, Finland, Belgium, Israel, Taiwan and
Korea, data about population can be obtained from continuously maintained
population registers, in which the name of each person in the country is
entered. Important migratory movements of individuals are also registered. The
primary objective of setting up this system of population registers is to
establish the identity of individuals and control them. The registers, however,
are also used to obtain such demographic information as current population
size, internal migration, data on vital events, etc.
Sample Registration Scheme
As you know, in every community records of births, deaths and marriages are
kept by either the local authorities or by religious'leaders. If these records are
complete and kept systematically, they can be used for estimation of fertility,
mortality and marriage rates.
However, there is one limitation. In our country these records are usually not
complete. This is because of ignorance, illiteracy, indifference and poor
systems of management. There is no incentive also to register deaths, births
and marriages. Hence, people usually do not report these vital events promptly.
Inspite of this, systematic analysis of these records do help to provide vital
statistics of some public health significance.
National Sample Survey
The main objective of the National Sample Survey has been to collect data on
some important socio-economic aspects on a comprehensive basis for the whole
country through its various rounds by using the technique of sample survey. .
The First Round of the National Sample Survey (NSS) was conducted in 1950;
since then, information on different items has been collected through various
rounds of the NSS. The topics covered so far include the following: fertility,
mortality, population growth, economically active population, family planning,
/
employment and unemployment, consumers, expenditure patterns, housing
conditions, manufacturing industries, physically handicapped persons.
Health Service Records
Information can also,be obtained from health service records kept by the health
sector for administrative purposes (e.g. maternal mortality in hospitals, disease
specific morbidity, information about birth weight, height during infancy and
childhood arm circumference of children, information on immunization and
prevention and control of certain endemic diseases).
Though health service records provide useful data for vital statistics, they have
their limitations unless kept properly. Their limitation is that they are kept for
administrative purposes rather than monitoring purposes and that too only at
places where health services are utilised.
Special Surveys
Household surveys undertaken by the members of a community, village agents,
local officials or researchers are very useful in providing information on age- .
specific and disease-specific mortality. These (when carried out at the national
level) are more frequently used for providing information for vital statistics1
rates.
Disease Registers
Disease registers maintained by various hospitals provide data on mortality and
morbidity for selected specific diseases and the treatment given.
8
