Optimum sampling strategy for
National Households In Abu Dhabi
(The Household Master Sample 2012)
Authors :
Mohammed Al Rifai (Ph.D.)
Mariam Al Qemzi
10/ October/2014
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Contents
 Introduction
 Problem Identification
 The Structure of Abu Dhabi Sampling Frame
 Master Sampling Frame and Stratification
 Stratification by Ratios of National Households
 Master Sample Size and Allocation
 Modified Allocation Criteria By Nationality Strata
 Conclusion
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Introduction
The Emirate of Abu Dhabi
• Almost 43 years since the formation of the UAE.
• UAE comprises Abu Dhabi plus six other Emirates.
• Abu Dhabi accounts for over 80 per cent of UAE land mass.
• Abu Dhabi contains around one third of UAE population.
• Emirati citizens make up around 20 per cent of Abu Dhabi
population.
• Abu Dhabi oil represents around 10 per cent of global reserves.
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Introduction
Statistics Centre – Abu Dhabi
• SCAD is the official source of statistical data for Abu Dhabi.
• Our Mission:
1. Develop and organize a statistical system in the Emirate.
2. Provide relevant and reliable official statistics serving policy makers, the
business community and the public.
• Celebrated five years of operation in April 2014.
• Operates in accordance with international best practice to provide range of statistics.
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Problem Identification
Households Type
Shared
18%
National
22%
Non National
60%
How to improve the sample strategy for national households, to ensure precise
and highly accurate estimates.
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The Structure Of Abu Dhabi Sampling Frame
Abu Dhabi three regions:
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The Structure Of Abu Dhabi Sampling Frame
Abu Dhabi Emirate
Regions (3)
Districts (117)
Sectors (1000)
EA (1883)
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The Structure Of Abu Dhabi Sampling Frame
Total No. EAs
% All
Households
% National
Households
% Non
National
Households
% Shared
Households
1,215
64.4
58
70.2
52.8
Al Ain
551
29.2
37
23.6
38.4
Al Gharbia
117
6.4
5
6.2
8.7
1,883
100
100
100
100
Region
Abu Dhabi
Total
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Master Sample Frame and Stratification
In 2012 Master sample:
•
Key Domains of Analysis:
–
–
•
Region
Citizenship
Levels of stratification of EAs:
Level 1
• Geographic domains which
Level 2
• Concentration of National
are the three regions of Abu
households within each
Dhabi Emirate
region
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Stratification by Ratios of National Households
The nationality strata are as follows:
Total No. of EAs
% National
Households for the
stratum
% All
Households
0 to 24.9%
1,315
7.3
69.9
2
25 to 49.9%
255
35.8
13.1
3
50 to 74.9%
199
61.7
11.1
4
75% or more
114
83.7
5.9
1,883
21.5
100
Stratum
Concentration of
National Households
1
Total
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Master Sample Size and Allocation
Master Sample size:
Number of PSUs in the master sample should be sufficiently large to provide
sample households for:
• Household surveys that are currently planned.
• Future Surveys – may require larger samples
• 4 Replicates.
Result - A sample of 560 EAs. This represents nearly 30% of all EAs used in
Census 2011.
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Master Sample Size and Allocation
Master sample allocation:
Allocation by region based on:
– previous sampling errors for key estimates of households surveys .
– 4 Replicates
EA allocation:
Region
EA count
Abu Dhabi
320
Al Ain
160
Al Gharbia
Total
80
560
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Modified Allocation Criteria By Nationality Strata
Proportional allocation adjusted by
K
h
as an adjustment factor ;
1  Kh  4
•
; h  1,...,4
The modified allocation criteria can be expressed as follows:
nh  n 
K h  Wh
4
 K
h 1
h
 Wh 
Where:
nh =
n =
Wh =
Nh =
N =
number of sample EAs allocated to stratum h.
total number of sample EAs
𝑁
weight assigned to nationality stratum h ; 𝑊ℎ = ℎ
𝑁
total number of households in nationality stratum h
total number of households in frame
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Modified Allocation Criteria By Nationality Strata
Stratum
EAs by National groups
% of All households
2
3
4
0 – 24.5%
25 - 49.9%
50 - 74.9%
75 – 100%
69.9%
13.1%
11.1%
5.9%
7.3%
35.8%
61.7%
83.7%
1
2
3
4
W
h
% National households
Adjustment factor
1
K
R
h
h
4
p

h 1
K h  Wh  Rh
4
 K
h  Wh

h 1
𝑝 ∶ The expected ratio of the national household in the sample
𝑅ℎ : Percentage of national households in the stratum (h)
𝑁
Wh : weight assigned to nationality stratum h ; 𝑊ℎ = ℎ
𝑁
K h : Adjustment factor, h  1,...,4
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Conclusion
Sample EAs by Region and Nationality Strata
Total
1
2
3
4
Estimated %
National
Households
in Sample
Abu Dhabi
Al Ain
Al Gharbia
320
160
80
155
65
39
58
23
22
67
39
10
40
33
9
33.3%
40.6%
29.9%
Total
560
259
103
116
82
35.6%
Nationality Stratum
Region
•
% National Households using proportional Allocation: 21.5%
•
% National Households using Modified Allocation: 35.6%
•
Implementation: high level of precision in LFS2012
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Contact
•
•
•
For more information please read the paper.
Website: www.scad.ae
Authors:
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