Country Course on Analysis and Dissemination of
Population and Housing Census Data with Gender
Concern
24-28 October 2011, Jakarta, Indonesia
In-depth Analysis of Census Data on Migration
Outline
 Migration as a Demographic Component
 Definition of Migration
 Types of Migration –Internal and International
 Sources of migration data
 Direct Measures of Migration
 Indirect Measures of migration
 Measurements of migration
 Place of Birth (POB) method
 Vital statistics method using demographic Balancing equation
 Survival ratio methods
 Forward survival method
 Reverse survival method
Migration as a Demographic Component
(Demographic Component/ Demographic Dynamics/ Demographic
process):
 Migration is a demographic component that determine the size, growth,
distribution and composition of population.
Migration – Migration is a movement from one geographical area to another
geographical area crossing the administrative boundaries for permanent or
semi permanent residence. The starting place is known “place of origin”
whilst the ending place is called ‘place of destination’.
- Internal Migration (migration within a country)
- External or International migration ( migration between countries)
Form of Internal and international Migration
 Form of Internal Migration:
 Rural to Urban (Rural – urban migration)
 Urban to Rural (Urban – rural migration)
 Rural to Rural (Inter- rural migration)
 Urban to Urban (Inter – urban migration)
 Form of International Migration
 Developing country to Developed
 Developing to Developing country
 Developed to Developing country
 Developed to developed country
Classification of Migration & Migrants
 Life – time migration (The place of birth is
different from place of residence).
 Recent – migration (The place of current residence
is different from the place of previous residence)
 POB Method id the way of deriving the life – time
migration or ever migration.
 A cross – tabulation of Previous versus current
residence is the way of deriving the recent
migration.
 Mass migration, force migration, return migration,
labour migration are the other groups of categories
of migration.
Sources of migration data
 Population censuses
 Population registers
 Sample surveys
 International migration statistics records
 Other sources
Measures of Migration
 Direct Measures:
 In-migration Rate (IR):
the number of in-migrants to a
physical/administrative area in a given year.
IR= The number of in-migrants to an area in given year x 1000
Mid year population
 Out-migration Rate (OR): the number of out-migrants
departing an area of origin, per 1,000 population at that area
of origin in a given year.
OR = the number of out-migrants in a given year x 1,000
Mid year population
 Net Migration Rate (NMR): the net effect of in-
migration and out-migration on an area’s population,
expressed as increase or decrease per 1,000 population of
the area in a given year.
NMR= Number of inmigrants-outmigrants x1000
Mid year population
or NRR = IR – OR
Gross Migration Rate: the total number of in-migrants and
out-migrants per 1,000 population of the area in a given
year
GMR = IR + OR
The above measures can be calculated for Gender as well.
Indirect measures of migration
 Why we need indirect measures:
 Unavailability of data for a small unit
 Defective of data
 Calculation to be made for specific concern
 To appraise the quality of migration data in a
Census.
 To project the migration by age or for future
Cont...
 Benefits of indirect migration estimates
 They can provide information through time, including
data for period and places where no other migration
statistics available
 They are applicable at all geographical levels from local to
regional and national populations
 Some of the methods provides estimates by age and sex
 Comparing estimates derived from different methods, can
be used to validate findings and the quality of data
Vital statistics method
 simplest and potentially most accurate method of
estimating net migration
 The Demographic Balancing equation can be used
 Net migration is obtained for each district/ region/area by
subtracting natural increase from the total population
change
Vital statistics method
 simplest and potentially most accurate method of
estimating net migration
 The Demographic Balancing equation can be used
 Net migration is obtained for each district/ region/area by
subtracting natural increase from the total population
change
Cont…
Demographic Balance Equation
Net Migration = ( P(t+1)- P(t))+Natural Increase or,
(Immigrants-Emigrants) = (P(t+1)- P(t) )+(BirthsDeaths)
Cont…
 Accurate estimation of net migration by this method
require accurate vital statistics on births and deaths
together with reliable census statistics or other data on
population change
 Develop countries vs. developing countries
Survival ratio methods
 Survival ratio methods involve 2 main steps
1. Calculate how many in a birth cohort survive from one
census to the next
2. Subtract the number of survivors from the cohort’s size at
the second census
The difference is the intercensal net migration
Cont…
 These estimates are usually do separately for males and
females to account age sex related variations in probabilities of
moving
 Data for survival ratio methods
 A sets of age – sex specific survival ratios
 Statistics on population by age and sex at two consecutive
censuses (5 year or 10 year)
Cont…
Calculation of age –sex specific net migration
A
Total
Aged
25-29
males
in
2000
B
C
Survivors
aged 30-34
in 2005
D=(C-B)
Total
Aged
30-34,
males
in
2005
Net
migration
Ages 30-34,
males
Survival ratio methods
 Survival ratio methods
 Forward survival method
 work forward through time
 Reverse survival method

Work backward through time
Forward survival method
 Estimate the net migration at the end of the interval
(i) Net migration gain
Net migration gain
Cohort population
size ages 20-24
Cohort population
size age 25-29
Estimated survivors
5 years
2000
2005
Cont…
 Forward survival method
(ii) Net migration loss
Net migration loss
Cohort population
size ages 20-24
Estimated survivors
Cohort population
size age 25-29
5 years
2000
2005
Cont…
 To estimate the net migration of people aged 25-29
at the end of the period, the estimated survivors
(from the original 20-24 cohort, by using
survivorship probabilities) are subtracted from the
total census population (second census) aged 25-29
in the area
 The estimated survivors from the initial cohort age
20-24, exceeded the census counts of 25-29 year old
in the second census, that means due to migration,
increase the cohort size or net migration gain to that
area
Cont…
 The formula for forward survival estimates of net migration is (Shryock and
Siegel,1973):
 Net M′x+n
= Pⁿ x+n – S x P0x
Where
Net M′x+n is the estimated net migration for the end-of-period population
age x+n
n is the interval in years between 2 censuses
P0x is the initial population aged x
Pⁿ x+n is the end-of-period population aged x+n
S is the survival ratio from age x to x+n
Reverse survival method
 Reverse survival method
 Provide a more complete estimate of the volume of net
migration, especially when the migration interval is long or
mortality is high
 Reverse survival usually produces higher estimates of net
migration because the figures include migrants who died
 Start with the end period ages from reverse survival estimates,
because some of the migrants would have died
 Reverse survival refers to migrants’ initial age
reverse survival method
(i) Net migration gain
Net migration gain
Cohort population
size ages 20-24
Cohort population
size age 25-29
Expected initial population
5 years
2000
2005
reverse survival method
(i) Net migration loss
Net migration loss
Cohort population
size ages 20-24
Cohort population
size age 25-29
Expected initial population
5 years
2000
2005
Cont…
 The formula for reverse survival estimates of net migration is
1
 Net M′x = ---- x Pⁿ x+n – P0x
S
Where
Net M′x is the estimated net migration for the initial population age x, obtained
by reverse survival
n is the interval in years between 2 censuses
P0x is the initial population aged x
Pⁿ x+n is the end-of-period population aged x+n
1
--S
is the reciprocal of the survival ratio from age x to x+n
 Reverse survival is obtained by multiplying end –period
population by the reciprocal of the survival ratio (i.e. 1/survival
ratio) and subtracting the initial population
E.g. if 5-9 age cohort size = 500 and
S x =0.87543
The number of survivors = 500 x 0.87543 = 437.715
Using reverse
The expected initial cohort size will be 437.715 x (1/0.875543) =500
migration estimates.xls
The birth place method
 Cross-tabulation of migration status & characteristics
•
Place of Usual Residence (POR) by Place of Birth (Birth place method)
-life time migration moves only
- severe underestimation migration moves
as intermediate destinations are not
recorded
 POR by POR 1 or 5 years ago
-
focus on recent migration flows
References:
- UN , 1970. Manual VI. Methods of Measuring Internal Migration.
Population Studies, No. 47. ST/SOA/Series A/47. Department of
Economic and Social Affairs New York
- UN, 1992. Preparing Migration Data for Subnational Population
Projections. ST/ESA/SER.A/127. Department of International
Economic and Social Affairs. New York
-
-
Zaba, B. 1985. Measurement of Emigration using Indirect
Techniques. Ordina Editors. Liege
Shryock, H.S. and J.S. Siegel. 1973. The Methods and Materials of
Demography. Academic Press, London.
Thank you