IFAD Vietnam RIMS Training Workshop 2011 (5 of 7)
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Transcript of IFAD Vietnam RIMS Training Workshop 2011 (5 of 7)
SAMPLING METHOD for ANNUAL SAMPLING METHOD for ANNUAL OUTCOME SURVEY OUTCOME SURVEY 3 PAD PROJECT in 3 PAD PROJECT in
BAC KAN PROVINCEBAC KAN PROVINCE
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Sampling Method for Annual Outcome Survey 3PAD project in Bac Kan Province
The project “Pro- Poor Partnerships for Agro- Forestry Development” include Pac Nam, Ba Be and Na Ri districts. All 48 communes in these three districts were covered by the project.
Sample size: 200 households 20 villages 10 households/village.
In-depth interviews and focus groups discussions will be implemented at each village
Sampling frame: list of all villages in 48 targeted communes
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Sample selection
- The selection of the sample is done in two stages: (1) selection of 20 villages; and (2) selection of 10 households in each village
- The sampling frame will be used every year, but the sample selection will be re-done every year. This mean that different villages and different households will be surveyed each year
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Step 2- Stage: Selection of 20 villagesThere are two options:Option A: if all villages covered by the project have
same socio- economic conditions, random selection can be done
Option B: If there are different groups of villages with different characteristics (for example some villages are located in lowlands, others in highland; or some villages are poorer than others), then the stratified sampling methodology needs to be used.
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Socio-economic condition of 3 target districts
- The 48 target communes in Ba Be, Na Ri and Pac Nam, of which 37 are eligible for P135 assistance mostly have greater than 85% ethnic minority, with 41 target commune having greater than 90 % ethnic households
So socio-economic condition of target districts is the same
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Random selection of 20 villages
Write down the list of all the villages targeted by the project, from 1 to total number of villages
The list of target villages were written as the following:
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Sampling frame (cont.)ID Village
NameID Village Name
1 Hát Lài 533 …………….
2 Xưởng Cưa 534 …………….
3 Hợp Thành 535 …………….
4 Bản Diếu 536 Khuổi Luông
5 Khuổi Luông 537 Bản Khúa
6 Thanh Sơn 538 Phja Đăm
7 Thôm Pục 539 Lủng Mít
8 Nà Nôm 540 Khuổi Mạn
9 Pan Khe 541 Bản Mạn
10 Pò Chẹt 542 Khau Bang
11 Khuổi Nằn 1 543 Khưa Lốm
12 ……………. 544 Nà Cà
13 ……………. 545 Nà Lại
14 ……………. 546 Nà Vài7
Sampling Interval (SI)
The number of sample size for survey is 200 households in 3 districts
We will select randomly 20 villagesCalculate the Sampling Interval (SI)
according to the formula below:SI= Total number of villages/20 = 546/20 = 27.3SI = 27
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Sampling Interval (SI)- Select a Random Number R between
1 and SI (27). To find a random number, you can use the Excel function Rand (Type = “rand ()* SI) in Excel worksheet) which gives a random number comprised between 0 and 1, and multiply this number by SI to get a number between 1 and SI
= rand()*27 = 3.2 Random Number = 3
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Sampling
- Select the Rth Village from the list. This is the frist village selected
for your sample. Add the sampling interval (SI) and select the next
village. This is the second village selected for your sample. Add
again the sampling interval and go to the next village, which will be
your third village. Continue like this until you reach 20 villages. If
you get to the end of the list, just continue from the beginning- Example
- R = 3 The 3th village (Hop Thanh) is selected
Formula for next villages:
3 + SI = 3 + 27 = 30 The 30th village (Khun Man) is selected3 0 + SI = 30 + 27 = 57 the 57th village (Na Ngoa) is selected57 + SI = 57 + 27 = 84 the 84th village (Pan Bai) is selected
Similar to above, we can select 20 villages10
Selected sampling list
ID Name village
ID Name village
1Hợp Thành 11Cốc Kè2Khun Mằn 12Nà Tạ3Nà Ngòa 13Kéo Pựt4Pác Sàn 14Nà Thẩu5Nà Khoa 15Nà Hai6Ca Đóm 16Nà Đúc 17Pàn Bái 17Khâu Phảng8Bản kẹ 18Bản Đính9Nà Quảng 19Lủng Phặc
10Pác Chi 20
Khuổi
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Option B: Selection of 20 villages through stratified random sampling
Stratified village categories
Number of villages
Lowland villages 90
Highlands villages 122
Total 212
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Option B (cont.)• Calculate the percentage in each group- % Lowland villages= (90/212)*100 = 42%- % Highland villages= (122/212) *100 = 58%• This tells us that, out of a sample of 20
villages: 42% should be villages in the lowlands (8
villages) 58% should be villages in highland (22
villages)
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Stage 2: Selection of 10 households in each selected village
Once having the list of 20 villages for collecting data, select randomly 10 households in each village.
Two options exist for selecting households in the villages, described below:(1) Option 1 is similar to the method for selection of the
villages. It is preferred over option 2. However, it requires to have a reliable list of all households living in the selected villages. If this information is not available, option 2 will be applied.
(2) Option 2 is cheaper and faster than option 1Choosing the appropriate method for household selection
depends on the information available and the logistics, time and resource constraints
More detailed information on sampling procedures is given in Annex II
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Option 1In each village, each household is given a unique
number (no two households can have the same number)Ex.: in the village there are 35 households are
numbered from 1 to 35A sampling interval (SI) is calculated by dividing the total
number of households by 10 Ex.: 35/10 = 3.4 SI = 4As in the selection of the villages, a random number
between 1 and SI is selected (for example, you can write numbers from 1 to 4 on small pieces of paper, fold them and ask someone to pick one paper) Ex.: The number 2 was picked. The household number 2 of the list is selected as the first household. Then add 4 (the sampling interval) and select the next household (household number 6). Add again and so on until reach ing household 10.15
Option 2Once the data collecting team arrives in the village, an
approximate center of the village is identified. A pencil or bottle is spun to select a random walking direction (also called a transect line)
The data collectin team counts the number of households encountered along the transect line between the centre and perimeter of the cluster (end of the village). This number is divided by 10 (total number of household needed) to determine the interval at which households will be selected in the transect line
When the transect line contains less than the number of households required, all households in the line are included in the sample and the data collecting team returns to the center of the cluster to pick a second random walking direction and the process is repeated.
This may require to return to the center and repeat the process if transects are fewer than the number of household required.16
Illustration image
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Sampling for a control group- Select 01 district in Bac Kan province with
the same socio-economic and geographically condition with 3 target districts in the areas project.
- These are the poor upland districts of Bac Kan province
- In 2010, there were 62 communes in Bac Kan covered by 135-II program. Among which, 12 communes in Ba Be, 12 in Na Ri and 10 in Pac Nam.
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Sampling frame for control group
Similar to building the sampling frame of the target districts:Sampling frame is a list of villages in selected district
Expected sample is about 80 households in each selected district.
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ExerciseDefine a sampling frame of a control
groupCalculate sample interval Select 10 households in each village
for survey.Develop a selected list of villages
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