Sources of Demo Data slides.pptx

DEMOGRAPHY
SOURCES OF DEMOGRAPHIC DATA

Sources of demographic data
Demographic data are of overstated importance in planning
purposes in all aspects of human development and
management and conservation of resources.
Demographic data can be categorized into several sources
including:
i) Census
ii) Vital registration
iii) Demographic Sample surveys
iv) Population Registers
v) International Publications

CENSUSES
Census is the common and main source of
demographic statistic data to date globally.
Census is defined as the process of collecting,
compiling, analyzing and publishing
demographic, economic and social data
pertaining, at a specific time, to all persons in
a country or delimited territory (Newell,
1988).

Features of census
The main features of the population
census include the following:-
 Sponsorship
Universality within a defined area
Simultaneity
Individual enumeration and
Defined periodicity

Census approaches procedures
The procedure to be used in enumeration
depends on the type of the information,
details and the nature and dispersion of the
population. The common enumerating
approaches include:
 A de facto approach
 A de jure approach and
A comprehensive approach

A de facto approach
A de facto approach of enumeration
approach of census collect information
from all individuals who were in a
specific locality during a census day,
regardless of whether they live there or
not. This approach therefore does not
differentiates between temporary and
permanent residents of that specific
area.

Weaknesses of the de facto approach
A de facto approach of enumeration
has two major bottlenecks, that are:
1. It does not put into account people
who will be on transit during the
census night
2. It may lead into false picture of the
actual demographic and population
data in those areas where there is
high migration rates.

A de jure approach
A de jure approach of enumeration
approach of census, collect information
from all individuals who are the
residents of the area where the census
exercise is taken, regardless of their
absence during enumeration. This
approach requires definition of people’s
permanent residence.

Weakness of the de jure approach
A major approach of the de jure
approach of enumeration is that
demographic and population data
from people who will be temporarily
away from their residential area, are
likely to be not counted.

A comprehensive approach
A comprehensive approach of
enumeration is the combination of
both the de facto and the de jure
approaches of census.
As it is the combination of the two
approaches, the comprehensive
approach is therefore more accurate
than the two approaches separately.

Advantages of census
1. It does not have sampling errors as the
enumeration covers the whole country/
locality
2. Because of it’s universality, census’s
results can be compared to those of
other countries
3. It is the most popular source of
demographic and population data as it
is normally taken at regular intervals

Weaknesses of census
1. Being an expensive exercise, it is often
postponed especially for the LDC. E.g in
Tanzania, the 1978 and 1998, were
postponed.
2. More often the developing countries seek
for financial assistances to make census
exercise a success and
3. It generally difficult to collect detailed
information as the exercise covers large
population/ area, normally being a country.

SAMPLE SURVEYS
In this method, demographic and
population data are collected from a
sample of the population or households.
In most cases, the sample is obtained
through various probability sampling
techniques such as probability sampling,
cluster sampling, systematic sampling
e.t.c.

Sample survey Cont...
a sample survey must be taken in such a
way that it can explain or describe as
accurately as possible, demographic
characteristics of the population it is
representing (wilson, 1985, newell,
1998).
in other words, a sample must be a
representative of the entire population
from which it was drown.

More often than not demographic sample
surveys looks at impact of economic,
social and environmental factors on
population and how the government
policies influence the levels and patterns
of health, mortality, fertility and
migration.

Type of sample surveys
There are two main types of sample
surveys that are: -
1. The single – round sample survey
This involves only one interview with the
respondents, designed for the large
sample and it is more convenient in
countries where addresses are not well
defined or where the population is
highly mobile.

2. The multi- round survey
This involves the re- interviewing of the
respondent several times. They are also
known as follow –ups or panel survey.
Demographic sample survey has become a
popular sources of demographic and
population data as census and Vital
registrations are very expensive, and it is
almost impossible to include census cannot
be more detailed as it not be manageable.

Merits of sample survey
1. Sample survey are simple and easy to
carry out and to administer
2. They are more flexible as compared to
census
3. It has relatively low cost
4. It can be used to collect detailed
information

Demerits of sample survey
1. Sample survey are subjected to
sampling errors
2. It is not easy to compare from one
country to another

Vital registration/civil registration
Vital event is the change of the
individual status that lead into change
of demographic and population data.
Some of the vital events include,
births , deaths and marriage
certificates. Other includes divorces,
separations, annulment, adoption
e.t.c.

Cont…
Vital registration (VR) and migration
control are also used in some countries
for legal purposes such as ( births,
deaths certificates, identification cards
and citizenship purposes just to
mention a few).

Cont…
The data that are collected through VR are
of paramount importance for
demographic analysis especially on
population dynamics/changes.
Although VR was initiated for the legal
purposes, such births, deaths and
marriages, still VR data are very important
for quantitative information and for
planning purposes. E.g business planning.

Uses of Vital Registration System
•Administrative purposes such as age,
nationality, birth place e.t.c
•Used for determining person eligibility
for things like, passports, voting, a
death certificates for family
entitlements
•Statistics use such as estimation of
seasonality of demographic events e.g
births, marriages, death to name a few.
•Checking quality of census

Cont..
•It is a continuous process of registering
demographic data.
•In some developed countries VR is compulsory
Weaknesses of the Vital Registration (VR)
•Not reliable source of demographic data in
Less Developed Countries (LDC)
•It is associated with recall errors E.g date of
event
•Lack of motivation to register events

Uses of population data
Uses of censuses
Census are useful for:-
•Planning and administration
•Economic and social research
•Estimating future population, size &
distribution
•Establishing links btn demography &
socio- economic processes
•Measuring levels & trends in standard of
living

Cont…
•Allocation of resources and services to
the population
Uses of Sample surveys
•Checking accuracy of population
censuses
•Estimation of components of
population change
•Estimating demographic variable in
population e.g age structure, marriage

Hints related to Demogr. Data
• Gender
• Age
• Ethnicity
• Location
• Education
• Marital Status
• Household Income
• Employment/Occupation
• Language
• Place of Birth
• Religion
• Political Affiliation
• Family and Dependents
• Voting Status

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