Abu Dhabi - IAOS 2014 Conference

Report
Optimum sampling strategy for
National Households In Abu Dhabi
(The Household Master Sample 2012)
Authors :
Mohammed Al Rifai (Ph.D.)
Mariam Al Qemzi
21/August/2014
www.scad.ae
Contents
 Introduction
 Problem Identification
 The Structure Of Abu Dhabi Sampling Frame
 Stratification Of The Master Sampling Frame
 Household Nationality Strata
 Master Sample Size And Allocation
 Proposed 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.
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.
3. Celebrated five years of operation in April 2014.
4. 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%
The problem:
“ How to improve the sample strategy for national households to ensure accuracy? ”
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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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Stratification Of The Master Sample Frame
•
Homogeneity of EA within Strata.
•
Key Domains of Analysis:
–
–
•
Region
Citizenship
Levels of stratification of EAs:
Level 2
Level 1
• Geographic domains which
• Concentration of National
are the three regions of Abu
households within each
Dhabi Emirate
region
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Households Nationality Strata
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 statistics.
– 4 Replicates
EA allocation:
Region
EA count
Abu Dhabi
320
Al Ain
160
Al Gharbia
Total
80
560
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The Proposed Allocation Criteria By Nationality Strata
•
The modified proportional allocation criteria can be expressed as follows:
Nh
Wh 
N
nh  n  4
Nh 

Wh 


N 
h 1 
Where:
nh =
n =
Wh =
Nh =
N =
number of sample EAs allocated to stratum h.
total number of sample EAs
weight assigned to nationality stratum h
total number of households in nationality stratum h
total number of households in frame
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The Proposed Allocation Criteria By Nationality Strata
Stratum
Concentration of National
Households
% of All households
% National households
Allocated weights
1
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
 ∶ The expected ratio of the national household ( p ) in the sample
ℎ : Percentage of national households in the stratum (h)
ℎ : weight assigned to nationality stratum h

ℎ : the ratio of sample size for stratum (h) to population size. (ℎ = ℎ )

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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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