Regional workshop on the Production of Population Estimates and Demographic IndicatorsAddis Ababa, 5-9 October
Evaluation and Analysis
of Age and Sex Structure
François Pelletier & Thomas Spoorenberg
Population Estimates and Projections Section
Evaluation method of age and sex distribution data
� Basic graphical toolso Graphical analysis
• Population pyramids
• Graphical cohort analysis
o Age and sex ratios
o Summary indices of error in age-sex data
• Whipple’s index
• Myers’ Blended Method
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Importance of age-sex structure
� Planning purposes – health services, education
programs, transportation, labour supply
� Social science, economist, gender studies
� Studying population dynamics – fertility, mortality,
migration
� Insight on quality of census enumeration
� Having strong effect on other characteristics of a
population
o Determined by fertility, mortality and migration, and follows
fairly recognizable patterns
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
What to look for at the evaluation
� Possible data errors in the age-sex structure, including o Age misreporting (age heaping and/or age exaggeration)
o Coverage errors – net underenumeration (by age or sex)
� Significant discrepancies in age-sex structure due to extraordinary events o High migration, war, famine, HIV/AIDS epidemic etc.
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Approaches to collecting age and its impact on quality
� Age - the interval of time between the date of birth and the date of
the census, expressed in completed solar years
� Two approaches
o The date of birth (year, month and day) - more precise information and is preferred
o Completed age (age at the individual’s last birthday) – less accurate
• Misunderstanding: the last, the next or the nearest birthday?
• Rounding to nearest age ending in 0 or 5 (age heaping)
• Children under 1 may be reported as 1 year of age
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Basic graphical methods – Population Pyramid
� Basic procedure for assessing the quality of census data on age and
sex
� Displays the size of population enumerated in each age group (or
cohort) by sex
� The base of the pyramid is mainly determined by the level of fertility
in the population, while how fast it converges to peak is determined
by previous levels of mortality and fertility
� The levels of migration by age and sex also affect the shape of the
pyramid
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Population pyramid – France, 1954 (Source: Pison 2014)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Population pyramid – France, 1974 (Source: Pison 2014)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Population pyramid – France, 2014 (Source: Pison 2014)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Population pyramid – High population growth
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
50,000 25,000 0 25,000 50,000
05
1015202530354045505560657075808590
95+
Population
Age Central African Republic, 1988 Census
MALE FEMALE
Wide base, triangle-shaped
pyramid indicates high fertility
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Population pyramid – Low population growth
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
500,000 300,000 100,000 100,000 300,000 500,000
0
5
10
15
20
25
30
35
40
45
50
55
60
65
70
75
80
85
90
95+
Population
Age Italy, 2011 Census
MALE FEMALE
“baby boom”
1940-45 Birth deficit
due to WWII
Flattening and narrowing base
Indicates long-term low fertility
Population pyramid – Detecting errors
� Age misreporting errors (heaping) among adults
� Under enumeration of young children (< age 2)
� High fertility level
� Smaller population in 20-24 age group
>> extraordinary events in 1950-55?
� Less men relative to women in 20-44 age group
>> labor out-migration?
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
320,000 220,000 120,000 20,000 80,000 180,000 280,000
05
101520253035404550556065707580
85+
Population
Age YEMEN, 1975 Census
MALE FEMALE
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
1,500,000 750,000 0 750,000 1,500,000
0-45-9
10-1415-1920-2425-2930-3435-3940-4445-4950-5455-5960-6465-6970-7475-7980-84
85+
Population
Age YEMEN, 1975 Census
MALE FEMALE
Population pyramid – Detecting errors
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
100,00075,000 50,000 25,000 0 25,000 50,000 75,000100,000
05
101520253035404550556065707580859095
100+
Population
Age TUNISIA, 1966 Census
MALE FEMALE
Age heaping
120,00090,000 60,000 30,000 0 30,000 60,000 90,000120,000
05
101520253035404550556065707580859095
100+
Population
Age TUNISIA, 1994 Census
MALE FEMALE
Declining fertility
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Population pyramid – Detecting errors
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
30,000 20,000 10,000 0 10,000 20,000 30,000
05
101520253035404550556065707580
85+
Population
Age Bahrain, 2010 Census
MALE FEMALE
500,000 300,000 100,000 100,000 300,000 500,000
0-4
10-14
20-24
30-34
40-44
50-54
60-64
70-74
80-84
Population
Age U.A.E., 2005 Census
MALE FEMALE
!!! Effect of Labor migration !!!
>> Importance of knowledge of the context
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Population pyramid – Line instead of bars
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
� Population Pyramid (bar chart)>> Not always easy to determine differences by sex
� Use of line chart
3,000,000 1,500,000 0 1,500,000 3,000,000
05
101520253035404550556065707580
85+
Population
Age Bangladesh, 2001 Census
MALE FEMALE
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80+
Po
pu
lati
on
Age
Bangladesh, 2001 Census
Male
Female
Population pyramid – Line instead of bars
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
3,000,000
0 5 10 15 20 25 30 35 40 45 50 55 60 65 70 75 80+
Po
pu
lati
on
Age
Bangladesh, 2001 Census
Male
Female
0
1,000,000
2,000,000
3,000,000
4,000,000
5,000,000
6,000,000
7,000,000
8,000,000
9,000,000
Po
pu
lati
on
Age group
Bangladesh, 2001 Census
Male
Female
Basic graphical methods – Graphical cohort analysis
� Tracking actual cohorts over multiple censuses
� The size of each cohort should decline over each census due to mortality (with no significant international migration)
� The age structure (the lines) for censuses should follow the same pattern in the absence of census errors
� An important advantage >> possible to evaluate the effects of extraordinary events and other distorting factors by following actual cohorts over time
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Graphical cohort analysis – Example (1)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
1997 Census 2007 CensusBirth Cohort
Male Female Male Female
0-4 1,353,206 1,388,350 2002-2007
5-9 1,112,321 1,113,675 1997-2001
10-14 947,236 878,429 1,222,668 1,183,939 1992-1997
15-19 774,327 854,078 925,729 991,323 1987-1992
20-24 637,113 827,614 774,413 986,526 1982-1997
25-29 509,109 654,465 707,603 841,416 1977-1982
30-34 410,148 477,562 583,689 667,865 1972-1977
35-39 373,813 428,395 481,396 556,191 1967-1972
40-44 270,046 303,147 366,518 389,087 1962-1967
45-49 257,070 282,098 321,236 328,660 1957-1962
50-54 178,902 212,060 231,232 283,288 1952-1957
55-59 162,122 174,234 194,011 208,657 1947-1952
60-64 114,335 125,096 140,146 159,557 1942-1947
65-69 100,425 109,288 113,840 127,794 1937-1942
70-74 47,407 50,607 72,288 81,329 1932-1937
75-79 41,529 42,858 55,448 61,012 1927-1932
80-84 15,305 17,326 22,417 28,278 1922-1927
85-89 16,576 19,448 1917-1922
90-94 4,803 5,883 1912-1917
� Data is organized by birth
cohort
� Exclude open-ended age
category
� People who were born in
the same years are
compared in the analysis
Source: United Nations Statistics Division,
Demographic Yearbook Statistical
Database
Mozambique, 1997 and 2007 Censuses
Graphical cohort analysis – Example (1)
Mozambique, 1997 and 2007 Censuses
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
1,600,000
1992
-199
7
1987
-199
2
1982
-199
7
1977
-198
2
1972
-197
7
1967
-197
2
1962
-196
7
1957
-196
2
1952
-195
7
1947
-195
2
1942
-194
7
1937
-194
2
1932
-193
7
1927
-193
2
1922
-192
7
1917
-192
2
1912
-191
7
1907
-191
2
Po
pu
lati
on
Birth cohort
Male - 1997 Census
Male - 2007 Census
MALE
0
200,000
400,000
600,000
800,000
1,000,000
1,200,000
1,400,000
1,600,000
1992
-199
7
1987
-199
2
1982
-199
7
1977
-198
2
1972
-197
7
1967
-197
2
1962
-196
7
1957
-196
2
1952
-195
7
1947
-195
2
1942
-194
7
1937
-194
2
1932
-193
7
1927
-193
2
1922
-192
7
1917
-192
2
1912
-191
7
1907
-191
2
Po
pu
lati
on
Birth cohort
Female - 1997 Census
Female - 2007 Census
FEMALE
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Graphical cohort analysis – Example (2)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
Po
pu
lati
on
Birth cohort
Male - 2000 Census
Male - 2010 Census
Republic of Korea, 2000 and 2010 Censuses, Men
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Graphical cohort analysis – Example (2)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Republic of Korea, 2000 and 2010 Censuses, Women
0
500,000
1,000,000
1,500,000
2,000,000
2,500,000
Po
pu
lati
on
Birth cohort
Female - 2000 Census
Female - 2010 Census
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Age ratios (1)
� In the absence of sharp changes in fertility or mortality, significant
levels of migration or other distorting factors, the enumerated size
of a particular cohort should be approximately equal to the average
size of the immediately preceding and following cohorts
� The age ratio for a particular cohort to the average of the counts for
the adjacent cohorts should be approximately equal to 1 (or 100 if
multiplied by a constant of 100)
� Significant departures from this “expected” ratio indicate either the
presence of census error in the census enumeration or of other
factors
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Age ratios (2)
Age ratio for the age category x to x+4
���� �2 ∗ ���
��� � ����
���� = The age ratio for the age group to � 4
5� = The enumerated population in the age category to � 4
��� = The enumerated population in the adjacent lower age category
���� = The enumerated population in the adjacent higher age category
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Age ratios (3) – example
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
0
0.2
0.4
0.6
0.8
1
1.2
1.4
5-9
10-1
4
15-1
9
20-2
4
25-2
9
30-3
4
35-3
9
40-4
4
45-4
9
50-5
4
55-5
9
60-6
4
65-6
9
70-7
4
75-7
9
Ag
e ra
tio
Age group
Mozambique – 1997 Census
Male
Female
0
0.2
0.4
0.6
0.8
1
1.2
1.4
5-9
10-1
4
15-1
9
20-2
4
25-2
9
30-3
4
35-3
9
40-4
4
45-4
9
50-5
4
55-5
9
60-6
4
65-6
9
70-7
4
75-7
9
80-8
4
85-8
9
Ag
e ra
tio
Age group
Mozambique – 2007 Census
Male
Female
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Sex ratios (1) - calculation
Sex ratio by age group
Sex Ratio = ���
�
���
�
or Sex Ratio = ���
�
���
�
∙ 100
Where
���
� = Male population enumerated in a specific age group
���
� = Female population enumerated in the same age group
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Value of sex ratio Interpretation
1 Same number of men and women in a given age group
Above 1 More men than women in a given age group
Below 1 Less men than women in a given age group
Sex ratios – Example (Expected sex ratio by age)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Source: United Nations Population Division, The World Population Prospects: The 2015 Revision
0
10
20
30
40
50
60
70
80
90
100
110
Sex
rat
io (
Nu
mb
er o
f m
en p
er 1
00 w
om
en)
Age group
Sweden, selected years 1950-2015
1950
1975
2000
2015
Sex ratios – Example
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
0
20
40
60
80
100
120
140
Sex
rat
io (
nu
mb
er o
f m
en p
er 1
00 w
om
en)
Age group
Mozambique, 1997 and 2007 Censuses
1997 Census
2007 Census
Rather sex ratio:
> Under-enumeration
of boys?
> Higher male child
mortality?
No decline at adult and older ages:
> Higher female mortality?
> Higher female out-migration?
> Under-enumeration of adult and older women?
> …
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Sex ratios – Cohort analysis
> Excess of men in
1975-1980 birth
cohort in 2000
census only
> Other age groups:
as expected
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
0
20
40
60
80
100
120
Sex
rat
io (
nu
mb
er o
f m
en p
er 1
00 w
om
en)
Birth cohort
Republic of Korea, 2000 and 2010 Censuses
2000 Census
2010 Census
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
Sex ratios – Cohort analysis
> Very different
patterns found in
each census
> Some consistencies
for birth cohorts
1947-1952 to 1927-
1932
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Source: United Nations Statistics Division, Demographic Yearbook Statistical Database
0
20
40
60
80
100
120
Sex
rat
io (
Nu
mb
er o
f m
en p
er 1
00 w
om
en)
Birth cohort
Mozambique, 1997 and 2007 Censuses
1997 Census
2007 Census
Summary indices – Whipple’s Index
� Developed to reflect preference for or avoidance of a particular terminal digit (or of each terminal digit)
� If heaping on terminal digits “0” and “5” is measured:
� ��������������…������!�"#
�∙�������$�����…��!#��!�"
∙ 100
� W ranges between 100, representing no preference for “0” or “5” and 500, indicating that only digits “0” and “5” were reported
� W is usually computed on the age range 23 to 62 >> childhood and older ages are often excluded because they are more strongly affected by other types of errors of reporting than by preference for specific terminal digits
Source: Shryock and Siegel (1980)
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Whipple’s Index (3)
The index can be summarized through the following categories:
>> these values must be interpreted keeping in mind the past and present context
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Value of Whipple’s index (W) Interpretation
<= 105 Highly accurate data
105 – 109.9 Fairly accurate data
110 – 124.9 Approximate data
125 – 174.9 Rough data
>= 175 Very rough data
Whipple’s index around the world (most recent census, 1985-2003)
Source: UN Demographic Yearbook special issue on age heaping: http://unstats.un.org/unsd/demographic/products/dyb/dybcens.htm
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Improvement in the accuracy of age reporting over time
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Whipple’s Index, Turkey 1950-2000
Summary indices – Myers` Blended Index
� It is conceptually similar to Whipple’s index, except that the index
considers preference (or avoidance) of age ending in each of the
digits 0 to 9 in deriving overall age accuracy score
� The theoretical range of Myers’ Index is from 0 to 90, where 0
indicates no age heaping and 90 indicates the extreme case where
all recorded ages end in the same digit
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Conclusion: Uses and limitations
� Assessment of the age and sex structure of a population
enumerated is typically the first step taken in evaluating a data
collection operation by means of demographic methods
� Demographic methods provide:
• A quick and inexpensive indication of the general quality of data
• Evidence on the specific segments of the population in which the presence of
error is likely
• “Historical” information which may be useful for interpreting the results of
evaluation studies based on other methods, and in determining how the
collected data should be adjusted for use in demographic analyses
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
Conclusion: Uses and limitations
� The major limitation of age and sex structure analysis is that it is
not possible to derive separate numerical estimates of the
magnitude of coverage and content error on the basis of such
analyses alone
� It is often possible to assess particular types of errors which are
likely to have affected the population counts for particular
segments of the population. Estimates of coverage error from other
sources often are required to verify these observations
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015
References
Pison, G. (2014), “1914-2014 : A century of change in the French population pyramid”, Population & Societies
No. 509 (March 2014)
Shryock, H. S. and Siegel, J. S. (1980), The Methods and Materials of Demography, Washington, D.C.: U.S.
Government Printing Office.
Moultrie T.A., R.E. Dorrington, A.G. Hill, K. Hill, I.M. Timæus and B. Zaba (eds), (2013), Tools for Demographic
Estimation, Paris: International Union for the Scientific Study of Population, available online at:
http://demographicestimation.iussp.org/
U.S. Census Bureau (n.d.), Population Analysis System (PAS), Washington, D.C., U.S. Census Bureau,
available online at: http://www.census.gov/population/international/software/uscbtoolsdownload.html
Regional Workshop on the Production of Population Estimates and Demographic Indicators
Addis Ababa, 5-9 October 2015