Evaluation of Census Data for the
General Population Census Data
of Cambodia 2008
BY: Mr. Meng Kimhor
Deputy Director General of NIS/MoP
Presented at Workshop on Census Data Evaluation for the South East
Asian Countries, Phnom Penh, Cambodia, 14-17 November 2011
1
Overview (1)
 Pop. Censuses in Cambodia:
 First Pop. Census 1962,
 Second Pop. Census 1998,
 Third Pop. Census 2008,
 There was a gap of 36 years between 1962 and
1998 because of conflict and civil war.
 The majority of the 1998 General Population
Census was supported fully by UNFPA. UNDP
provided vehicles, but took them back.
 2008 Pop.Census was supported by UNFPA, JICA,
Japanese Gov’t, Germany Gov’t, and RGC
 The de facto was used for 1998 and 2008
population census.
2
Overview (2)
 Post-enumeration Survey (PES) was conducted
immediately after a census for the purpose of evaluating
the census quality (from 25 March to 04 April, 2008).
 The Provincial Planning Director and Deputy Director in
each province coordinated and supervised the PES
operations in the respective province.
 About 200 enumerators and supervisors carried out the
field task.
 The net coverage error of missed persons (2.77 percent)
and the level of response variance of selected
characteristics as estimated by PES show that in the
general 2008 General Population Census of Cambodia
was conducted satisfactorily.
3
Objective
• The main objective of PES is to quantify the
omission and duplication and ultimately
estimate in the net error in the census count,
and also to measure the response errors in
respect of a few selected characteristics
canvassed in the census.
• Apart from evaluation, the PES provides a
feedback on operational issues which will be
useful while organizing future censuses.
4
Method Used To Evaluate 1998
and 2008 Census Data
 Recruit enumerators and supervisors for field task (200 Enu. and Sup for PES of
2008 census).
 Sample Design: the sample plan for conducting the PES was very simple. It is a
probability sample selected in single stage, using systematic random sampling.



Sample Frame: The sample frame for the PES was the final list of
Enumeration Area (EAs) in Cambodia they were to be covered by the 2008
General Population Census. There were about 28,000 EAs listed for the
census.
The sample selected consisted of 100 EAs. The selected EAs were reenumerated for PES. The overall size of the PES sample that was selected
about 9,600 households with 46,000 persons for 2008 and in 1998 census
PES sample was selected 8,703 households or 45,021 persons.
Sample selection: After sorting the EAs in the sequence indicated the sample
was selected at the rate of 1 in 282.6 using a random start for 2008 census
and 1998 census, the sample was selected at the rate of 1 in 249.2, using
random start of 78.9. The sample was systematic, equal probability selection
design as geographic ordering, urban and rural, EAs arranged in order of their
estimated sizes within each urban or rural sector.
5
Method Used To Evaluate 1998
and 2008 Census Data (2)
 Limitation of PES: many countries undertake post-census studies by
re-checking a sample of the census returns, in one way or anther, to
try to measure the degree of undercounting.
 Training and Fieldwork: There were three distinct stages of
operation in the PES such as: i) Listing and enumeration of persons
in all households in buildings situated within the allotted
Enumeration Area (EA), ii) Desk matching of particulars collected
during listing with those contained in the corresponding census
schedule, Form B, and iii) Field recollection of particulars, where
necessary.
 Some Important Aspect of PES Procedure: In order to minimize the
non-sampling error in conducting PES field operation the following
situation that occurred during the PES re-enumeration were
reconciled with the census in order to determine true census misses:
i) Births, ii) Deaths, and iii) In-movers and out-movers
6
Main results of evaluation
of Census Data
7
Estimates of coverage error
Estimate
Completion rate
Missed rate
Over-count rate
Net missed rate
Percent
2008
1998
98.22
2.15
0.37
1.78
97.23
3.39
0.62
2.77
8
Net missed rates by age group
and sex for 1998 census (percent)
Age group
Both Sexes
Males
Females
All ages
1.78
1.81
1.76
Under 1
0-9
19-Oct
20-29
30-39
40-49
50-59
60+
4.64
1.78
1.49
3.14
1.84
1.18
0.91
1.56
4.04
1.63
1.34
3.48
2.44
1.41
1.04
1.02
5.29
1.94
1.63
2.85
1.34
1.01
0.82
1.96
9
Data Evaluation
10
Standard Error of Census
Coverage Estimates
Item statistics
Gross under-count (Missed persons)
Gross over-count (Over counted persons)
Net under-count (Net missed persons)
Net missed rate
Coefficient of
variation %
2008
1998
1998
2008
1998
2008
250,626 466,597 23,095 62,619
9.21
13
42,994 84,795 7,402 14,468 17.22
17
207,632 381,802 24,192 62,450 11.65
16
0.178 0.0277 0.002 0.0045 11.24
16
Estimate
Standard Error
11
Net Undercount Rates
in some countries
Countries
Australia
Bangladesh
Canada
Cambodia
China
India
New Zealand
United Kingdom
Year
1996
1991
1991
1996
1998
2008
2000
1991
2001
2001
2001
Net undercount
rate (%)
1.6
4.6
2.9
2.4
1.8
2.8
1.8
1.7
2.3
2.2
2.2
12
Level of Agreement
13
Rate of Agreement and Aggregate
Inconsistency Index for selected characteristics
Characteristics
Index of Inconsistency
(IAG )
1998
Age
2008
Rate of Agreement
1998
2008
12.08
5.6
89.1
94.8
Mother tongue
4.97
13.3
99.4
99.4
Marital Status
NA
7.1
NA
95.9
16.3
7.7
91.0
97
NA
14.1
NA
98.9
Main activity
17.47
19.0
88.0
89.5
Employment period
44.34
43.2
84.0
75.1
Children ever born
15.60
16.0
86.0
90.3
Children surviving
10.18
19.0
91.4
86.5
Literacy
Physical/Mental
Disability
14
Net Difference Rate and Inconsistency
Index of enumerated by age
Age Group
0
1-4
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+
Net Difference Rate
1998
-0.02
0.16
NA
-0.02
-0.05
-0.09
0.10
0.01
0.07
-0.08
0.00
-0.13
0.02
0.02
0.02
-0.05
0.03
2008
NA
NA
-0.2
0.2
-0.1
-0.1
0.1
0.1
0.1
N
-0.2
0.1
N
-0.1
N
N
N
Index of Inconsistency
1998
11.25
9.47
NA
11.19
11.50
9.95
13.86
12.55
13.49
13.44
13.89
14.70
15.10
14.70
15.96
17.16
7.40
2008
NA
NA
7.4
7.8
5.9
2.1
3.2
3.2
8.4
5.3
4.6
4.9
9.5
6.3
6.8
15.6
5.1
15
Net Difference Rate And Inconsistency Index for
Person Enumerated By Marital Status- Cambodia
Marital Status Category
Net Difference
Rate
Index of
Inconsistency
Never married
0.6
3.2
Married (i.e. currently married)
0.3
5.3
Widowed
-0.7
14.3
Divorced
-0.3
24.5
0.1
14.3
Separated
16
Net Difference Rate And Inconsistency Index for
Person Enumerated By Type of Physical/Mental
disability-Cambodia
Type of Disability
None
In seeing
In speech
In hearing
In movement
Mental
Net Difference
Rate%
1.3
-0.4
0.1
N
-0.5
-0.3
Index of
Inconsistency
16.3
2
11.2
N
10
5.8
17
Net Difference Rate And Inconsistency Index
for Mothers classified by children ever born
Category
(Number of
Children Ever
Born)
0
1
2
3
4
5
5+
6
7
8
9
10+
Not Stated
Net Difference Rate (%)
1998
0.91
0.44
0.39
-0.11
0.19
0.02
NA
-0.05
-0.39
-0.22
-0.5
-0.66
-0.02
2008
Index of Inconsistency
1998
1.3
0.2
0.6
0.6
-0.3
NA
-2.3
NA
NA
NA
NA
NA
NA
4.28
11.78
14.8
16.11
19.83
21.13
NA
22.44
22.24
22.65
25.64
29.13
12.51
2008
7.3
16.7
16.7
14.8
15.4
NA
9.6
NA
NA
NA
NA
NA
NA
18
Net Difference Rate And Inconsistency Index
for Mothers classified by children surviving
Category
(Number of
Children Ever
Born)
0
1
2
3
4
5
5+
6
7
8
9
10+
Not Stated
Net Difference Rate (%)
1998
2008
0.77
0.14
0.02
-0.22
-0.07
0.08
NA
-0.17
-0.14
-0.25
-0.12
-0.03
-0.01
Index of Inconsistency
1998
2.3
-0.9
-0.9
1.6
-0.3
NA
-1.8
NA
NA
NA
NA
NA
NA
4.27
9.51
10.77
11.51
11.2
13.52
NA
14.21
15.76
16.24
17.29
20.14
12.51
2008
13.2
18.4
16.9
22.5
21.8
NA
12.2
NA
NA
NA
NA
NA
NA
19
Problems faced (1)
• There were some problems at the household
listing as households increased. In some
EAs, the households increased to three or
four times as compared with the results of the
census mapping. Therefore the NIS faced
the problem to print and send additional
forms to the relevant EAs.
• Printing a large volume of census forms and
distributing them to the field on time was very
crucial.
20
Problems faced (2)
• Difficulties in enumeration in urban areas:
– Multiple store building;
– Locked houses;
– Vacant houses;
• During PES operation, some respondent forget
some information that they answered during
census time (hour 00 in 3 March 2008)
21
Conclusion
• The PES is the one method to evaluate the census data in 1998 and
2008
• Through the PES, the 1998 and 2008 population census can be
estimated over-count (duplicate plus erroneously counted) is only
0.37 in 1998 and 0.62 in 2008.
• The quality of enumeration was generally good as revealed by the
level of response variance is selected characteristics, age, martial
status, mother tongue, literacy physical/mental disability, main
activity, the aggregate level of inconsistency is moderate.
• The net coverage error of missed persons is 1.78 percent in 1998
population census and 2.77 percent in 2008 population census. So,
the generally the 1998 and 2008 was conducted satisfactorily.
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