Transcript EVALUATION OF THE 2003 POPULATION CENSUS DATA THE …

EVALUATION OF THE 2003
POPULATION CENSUS DATA
THE GAMBIA
BY MR. ALIEU SARR
PRESENTED AT THE UN REGIONAL WORKSHOP ON CENSUS
EVALUATION AND POST-ENUMERATION SURVEYS, ADDIS ABABA,
ETHIOPIA, 14TH – 18TH SEPTEMBER 2009
EVALUATION OF AGE

Age misreporting is a common phenomenon in African
censuses
 This may be due to Ignorance of actual age;
 Deliberate attempt to increase or decrease age for
one reason or the other
Why evaluate the quality of age reporting?
1.
2.
3.
4.
To establish the consistency of the data.
Reveal past trends in fertility.
Identify errors in reported ages.
Determine the effects of migration on age structure.
EVALUATION OF AGE (cont.)
Indices of Evaluating Age and Sex:
Sex Ratios: The larger the departure of the
Sex Ratio from 100 the larger the
possibility of errors in the data.
Age Ratios: All Age Ratios should be
closed to 100 where fertility has not
fluctuated a lot during the past and
international migration has not been
significant.
Age-sex Accuracy index:
Population Pyramid of The Gambia 2003
75
70
65
60
Male
Female
55
50
45
40
35
30
25
20
15
10
5
0
(21,000)
(16,000)
(11,000)
(6,000)
(1,000)
4,000
9,000
14,000
19,000
Population by Age and Sex, The Gambia, 2003
Female
Age-Group
Male
75- 9 8
70 - 74
6 5- 6 9
60-64
55- 59
50 - 54
4 5- 4 9
40-44
3 5- 3 9
30-34
2 5- 2 9
20-24
15- 19
10 - 14
5- 9
0-4
8
7
6
5
4
3
2
1
0
0
2
4
6
8
Sex Ratio by LGA
The Gambia 1993
120
115.1
110.4
107.1
103.1
102.5100.1
100
93.9
96.1
90.1
96.6
91.8
97.5
91.8
99.9
92.9
92.5 90.2
80
60
40
20
a
bi
se
am
G
Th
e
ng
na
Ja
Local Government Area
Ba
s
bu
re
h
r
ta
u
un
K
er
ew
K
on
sa
k
an
ko
a
m
M
an
Br
ik
a
K
an
ju
ifi
ng
l
0
Ba
n
Sex Ratio
The Gambia 2003
97.1
Myers’ Index of Age Heaping by LGA
65
The Gambia 1993
The Gambia 2003
60.7
55.8
55
55.7
54.7
53.1
52.1
48.8
51.7 51.9
50
43.8
45
42.1
35
33
28.2
25
23.4
23.9
15
Local Government Area
The Gambia
Basse
Janangbureh
Kuntaur
Kerewan
Mansakonko
Brikama
-5
Kanifing
5
Banjul
Myers' Index
38.1
Summary of Indices Measuring the Accuracy of Data,
1993 and 2003 Censuses, The Gambia
Index
Reported, 1993
Census
Reported, 2003
Census
Sex ratio score
15.5
9.4
Male age ratio
score
Female age ratio
score
Accuracy index
10.6
8.8
22.4
15.9
79.4
52.9
The UN defines the values of the index as follows:
< 20
Accurate,
20-40 Inaccurate,
40 +
highly inaccurate
Key Findings
• Sex-ratio in urban areas is above 100, whilst that
of rural areas is below 100
• Under-reporting of under-five population
• Age data are relatively more accurate in urban
than in rural areas
• Age data for males are relatively more accurate
than that of females
• Age-sex data in 2003 is relatively more accurate
than that of 1993
• Level of accuracy of age data below
recommended standards
Correction of Age Misreporting
Methods of Smoothing Age Misreporting;
• Smoothing without modifying the totals of
each age-group
• Smoothing modifying the totals of each
age-group
• Smoothing of age structure can be done
using spreadsheets such as; SINAGE,
AGESEX and AGESMTH
Figure 2.2a: Re porte d and Sm oothe d Male Population by Age , 2003 Ce ns us
120,000
100,000
80,000
60,000
40,000
20,000
0
0- 4
5- 9
10- 14
15- 19
20- 24
25- 29
30- 34
35- 39
40- 44
45- 49
50- 54
55- 59
60- 64
65- 69
70- 74
Age
Re porte d
CF
K.-King N Male
Arriaga
UN
Strong
75- 79
Figure 2.2b: Reported and Sm oothed Fem ale Population, 2003 Census
120,000
100,000
80,000
60,000
40,000
20,000
0
0- 4
5- 9
10- 14
15- 19
20- 24
25- 29
30- 34
35- 39
40- 44
45- 49
50- 54
55- 59
60- 64
65- 69
70- 74
Age
Reported
CF
K.-King N
Arriaga
UN
Strong
75- 79
Evaluation of Data on Children Ever Born
Questions Asked to Determine Parity for
Females aged 12 years and Over:
• Of the children ever born alive to you,
how many are living in this household?
• Of the children ever born alive to you,
how many are living elsewhere?
• Of the children ever born alive to you,
how many have died?
Evaluation of Data on Children Ever Born (cont.)
How do we evaluate the data on children ever born?
• Average parities should increase by age of women.
Average parities for the 2003 census progressively
increased with age of women showing some consistency
in the data.
• When parity not stated is less than 5 per cent, they can
either be ignored or added to the denominator since their
inclusion or exclusion will not affect the estimates. The
parity ‘’not stated’’ for the 2003 Census data was 2.5 per
cent.
• Coale-Demeny and Brass empirical formulae to compare
the results with the average parity for women 45-49 or
P7. If the average parity for women 45-49 is lower than
that estimated from the empirical formulae, then this can
be an indication that there was under-reporting or
omissions of children for women 45-49 years.
Average Parities, The Gambia 2003
Age Group
15-19
20-24
25-29
30-34
35-39
40-44
45-49
Index
1
2
3
4
5
6
7
Average Parity
0.190
1.107
2.487
3.884
4.873
5.482
5.609
Evaluation of Data on Average Parities
• Using the data from Table 2.1 above, the Coale-Demeny
empirical formula is as follows:
(P3)2/P2 = (2.487)2/1.107 = 5.588
• The Brass empirical formula yields the following result:
(P2)(P4/P3)4 = (1.107) (3.884/2.487)4 = 6.581
• P7 or reported average parity for women 45-49 from
Table 2.1 above is 5.609
• Coale-Demeny formula compares favourably with the
parity for women 45-49, which means there were no
under-reporting or omissions of children by older women.
However, the estimates from Brass formula indicate that
there were under-reporting of children. The Brass
formula provides a more robust estimate.
Evaluation of Data on Average Parities (cont.)
• Evaluation of data on children born during
the year preceding the census showed
some inconsistencies in the data with an
over-reporting of births in the year
preceding the census.
General Conclusion:
• There has been a general under-reporting
of children of women in the older ages.
Deaths in the Year Preceding the Census
Methods of Evaluation Data:
• Growth Balance Method developed by
Brass
• Preston-Coale (PRECOA)
Deaths in the Year Preceding the Census (cont.)
Results of Evaluation:
• Reporting of deaths more accurate in the
older ages than the young
• Reported male deaths more accurate than
female deaths
• Female deaths under-reported by 12.3 per
cent
• Male under-reporting negligible
Recommendations
• Improve on enumerator training to improve
accuracy of estimating age using existing
techniques;
• Minimize data collection through proxy
interviews during census taking;
• Institute stricter measures to ensure the
recruitment of qualified enumerators and
supervisors;
• Put in place measures to improve on the
quality of supervision during census taking
Thank you for the attention.