Transcript Slide 1

United Nations Department of Economic and Social Affairs – Population Division
Population Estimates and
Projections Section
Work Program, Outputs, Challenges, Uncertainties
Gerhard K. Heilig
Patrick Gerland, Kirill Andreev, Nan Li, Danan Gu, Thomas Spoorenberg
Sarada Ravinuthala, Chandra Yamarthy, Neena Koshy
United Nations, Department of Economic and Social Affairs (DESA), Population Division
www.unpopulation.org
2 May 2012
United Nations Department of Economic and Social Affairs – Population Division
Work Program
Prepare the World Population Prospects
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Official United Nations population projections, used throughout the UN System
Recent revisions prepared every second year
Latest revision: 2010 (230 countries)
22 revisions since the early 1950s
Prepare the World Urbanization Prospects
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Estimates and projections of urban population for 230 countries
Estimates and projections of major urban agglomerations (about 5000)
Latest revision: 2011
Since 1988
Publish results, develop methodology
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Web sites, wall charts, CD-ROMs/DVDs, databases
Model life tables, probabilistic projections (Bayesian Hierarchical Model)
Develop specialized databases and software
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DemoBase, DemoData, DataArchive
Estimation and projection software, probabilistic models, data checking
United Nations Department of Economic and Social Affairs – Population Division
Preparation: World Population Prospects
Start of
WPP
Data Collection, Estimation
0
Start of
WUP
1
Data Collection
230 countries / areas
Evaluation
Adjustments
Epidem. Modeling
Projection,
Aggregation, Checking
Uploading to Database
Calculation of Variants
2
Output Production
Early Release Data
Aggregation of Regions
Online Data
Web Site
Checking of Results
CD-ROMs / DVDs
Fixing of Errors
Statistical Reports
Vol. 1, 2
Consulting / Feedback
Wall Chart
15% of Workload
Methodological Report
(on web site)
for AIDS Countries
60% of Workload
Update and development of new
databases and software, server
and database maintenance, backup
Responding to clients
25% of Workload
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United Nations Department of Economic and Social Affairs – Population Division
Data Sources
1.
Census data + post-enumeration surveys
2.
All available demographic and health surveys
3.
Estimates from population and vital registers
4.
Scientific reports and data collections
5.
Data and estimates provided by other international
agencies (CELADE, Regional Commissions, EUROSTAT, ESCAP,
(from United Nations Demographic Yearbook database and directly from
National Statistical Offices)
(DHS, DSS, MICS, WHS, etc.) for estimating fertility and mortality
(from statistical reports of National Statistical Offices or their web sites)
(Human Mortality Database, child mortality estimates, etc.)
UNICEF, UNAIDS, WHO)
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Uncertainty of Projections
0
Minimal uncertainty
(adult mortality)
Cohort
Some uncertainty
(second generation fertility,
child mortality)
Little uncertainty
(first generation fertility,
child mortality)
Age
Period / Year
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
United Nations Department of Economic and Social Affairs – Population Division
Estimation of Total Population
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Estimation of population by age and sex
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Estimation of Population from Censuses
Under-reported migrant workers
Under-reported births
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Estimation of Fertility: ASFR (Bangladesh)
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Data Problems
No recent census available (latest census 10 or more years ago)
Only headcount of census was published. Population by age and sex was not
published.
No data on fertility and mortality were available from the census (such as
children ever born, children born during 12 months prior to enumeration,
deaths during 12 month prior to enumeration).
Census diverts significantly from previous population trends. Census
population by age and sex cannot be reproduced from the previous census
by using inter-censal statistics or estimates on births, deaths, and
migration.
Examples: Turkey 2007 register-based census; Bangladesh 2001 population census;
Equatorial Guinea, 2001 census
Obviously manipulated census counts, such as in countries, where the
published census count is exactly 300,000 or grossly overestimated to meet
a particular, politically relevant threshold (such as 1 million).
Examples: 1983 census of Equatorial Guinea; 1969 census of Bhutan.
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Data Problems
Divergences in fertility data between different official sources, such as
differences between statistical data published by various ministries.
Example: In China, fertility estimates range from 1.38 for 2006 (2006 National Sample Survey
on Population Changes) to 1.8 for 2007 (Statement by Dr. Hao Linan, Director-General for
International Cooperation of the National Population and Family Planning Commission of China
at the General Debates of the 41st Session of the UN commission on Population and
Development. New York, 8 April 2008).
Divergences in mortality estimates (under-five mortality, infant mortality) from
different sources, such as vital registers, surveys, censuses as documented
by UNICEF
Incomplete geographical coverage of censuses and surveys due to armed
conflicts or other problems
Example: Democratic Republic of the Congo, Sri Lanka (Tamil Region), Sudan (Darfur)
Lack of meta-information and quality measures for census and survey data.
Post-enumeration survey for census was not carried out or results are not
available. Sampling plan for population survey is not available. No
information about representativity of survey.
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Data Problems
Incompatibility of subsequent census counts due to change of enumeration
method, such as register-based data collection.
Examples: Turkey 2007 address-based census, Brazil
Incompatibility of subsequent census counts due to change of definitions,
such as the change from de-facto population to de-jure population.
Incompatible definitions: resident population
Examples: Hong Kong, Singapore, Qatar
Highly disputed statistical data on mortality, fertility or migration due to war, civil
war, natural disaster. Unlikely sex ratios at birth.
Examples: Mortality estimates of Iraq during embargo and war; China’s “missing girls”
Extremely volatile population changes within short periods due to (labor)
migration, particularly in countries where a large percentage or even the
majority of the de-fact population is foreign labor migrants.
Examples: Qatar
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Model of fertility decline
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Model: Bi-logistic function to estimate the rate of fertility decline
k1
k2
P(t ) 
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Ln(81)
Ln(81)
1  exp[
(t  tm1 )] 1  exp[
(t  tm 2 )]
t1
t2
Parameter
k1 ...............
Δt1 ..............
tm1 ..............
k2 ...............
Δt2 ..............
tm2 ..............
Slow/Slow
Fast/Slow
Fast/Fast
-0.11
5.03
5.77
0.15
2.75
3.21
-0.16
4.34
5.06
0.22
3.02
3.52
-0.25
4.01
5.17
0.31
4.32
3.94
In probabilistic fertility projection: Parameters values are replaced
by distributions. Some 100,000 trajectories of fertility decline are
calculated by sampling from these parameter distributions.
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
United Nations Department of Economic and Social Affairs – Population Division
BHM: A fertility transition model
Phase I: Not modeled.
Phase II: Fertility transition, modeled by
Bayesian Hierarchical Model (BHM)
Phase III: Modeled with a first order
autoregressive time series model [AR1],
with its mean fixed at the approximate
replacement-level fertility of 2.1
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Probabilistic projection of total fertility
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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671 million
United Nations Department of Economic and Social Affairs – Population Division
Uncertainty
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1.12 billion
452 million
United Nations Department of Economic and Social Affairs – Population Division
Probabilistic Projection of Population: Japan
Total Population
Population age 15-64
Based on estimates from WPP2010; probabilistic fertility, deterministic mortality
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Probabilistic Projection of Population: Ukraine
Total Population
Population age 15-64
Based on estimates from WPP2010; probabilistic fertility, deterministic mortality
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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Europe
NA Latin America Caribbean
Asia
1950 - 2100
United Nations Department of Economic and Social Affairs – Population Division
All colored countries are below 2.1 TF (1950-2100)
Based on WPP2010
230 Countries
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
Africa
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Population in million
United Nations Department of Economic and Social Affairs – Population Division
World population by Total Fertility, 1950-2100
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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Billions
United Nations Department of Economic and Social Affairs – Population Division
Total Population by Variant, 1950-2100
27 Billion
16 Billion
10 Billion
6 Billion
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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Persons per square kilometre
United Nations Department of Economic and Social Affairs – Population Division
Population Density: Selected Countries, 1950-2100
6.6 times density of Japan
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Population Age 0-19 and 50+ Years
Age 0-19
Age 50+
The world is ageing!
50+ population will increase from 1.4 to 4 billion
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Millions
United Nations Department of Economic and Social Affairs – Population Division
Population Age 15-34 by Major Area, 1950-2100
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Uncertainty / Problems
1. in the quality of empirical data on population, fertility,
mortality and migration available
(We are not dealing with HMD world.)
2. in the methods to evaluate and, if necessary, adjust and
re-construct demographic statistics
(Inconsistencies: previous censuses; data from neighboring countries; new states)
3. in the methods we use for projecting fertility, mortality,
and migration
4. Calculation errors during estimation, projection,
aggregation, and publication of results
(interpolation, aggregation, calculation of life tables, treatment of migration)
United Nations Department of Economic and Social Affairs – Population Division
WPP / WUP: Web Sites
http://esa.un.org/unpd/wup/
http://esa.un.org/unpd/wpp/
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
United Nations Department of Economic and Social Affairs – Population Division
Data Checking
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Databases - Example: DemoData
Different Data Sources
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York
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United Nations Department of Economic and Social Affairs – Population Division
Team
Chief
Gerhard K. Heilig
Population Affairs
Officer
Population Affairs
Officer
Population Affairs
Officer
Population Affairs
Officer
Population Affairs
Officer
Kirill Andreev
Patrick Gerland
Danan Gu
Nan Li
Thomas
Spoorenberg
Information
Systems Assistant
Information
Systems Assistant
Sarada
Ravinuthala
Chandrasekhar
Yamarthy
Editorial Assistant
Neena Koshy
United Nations Department of Economic and Social Affairs – Population Division
Thank You !
www.unpopulation.org
Source: United Nations, Department of Economic and Social Affairs, Population Division (2011): World Population Prospects, the 2010 Revision. New York