How to Develop Master Sampling Frames using Dot Sampling Method

and Google Earth

Issei Jinguji. Agricultural statistics. JICA expert.

Project for Capacity Development for the ASDP Monitoring and Evaluation System Phase Ⅱ, Dar es Salaam. Tanzania

Rome Italy, 5 December, 2012

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1 Introduction

We have experienced planted area sampling surveys based on the list frame method, physical area frame method, and square area frame method.

But these were not appropriate methods for the developing countries.

Last year, we found the “Dot Sampling Method” using Google Earth. It is very effective and reliable. Now, we are establishing a system which is called “Dot Sampling System” which generates dots or area frames.

The system might be the most promising system to

generate a “Master Sampling Frames” without cost across the regions and time.

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2 Development of the dot sampling method (1) Assessment of Frames

① List frame method (Interview )

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• It is said “easy method”, but, you need to make list frame (need to conduct Population census or Agricultural census).

• You need to up-date the list (goes out-of –date quickly).

• You need to make stratums.

• You need to visit sample farmers and interview with them.

• Non-sampling errors occur.

• You need on-going maintenance.

Formula(Two- stage sampling):

②Area frame method （Segments with physical boundaries method）

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It is said “reliable method” You need to prepare maps (expensive), Need to make frame drawing boundary(hard work), You need to make list. You need to measure area at samples (hard work). You need to up-date. This is Japanese method. But now, it is moving on the next methods.

③ Area frame method (Square segments: mesh frames method)

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1 2 3

21

7

20 19

13 14 15 16 17 18

9 10 11 12

6 5 4

24 23

22

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This is “the improved method”. You do not need to draw boundary-lines to make frames. But, you need to buy GIS (expensive) to make frames. You need to learn GIS operation. You need powerful PCs to build mesh frames. You need to measure area at samples (hard work).

These three methods were established method, but we were not satisfied.

(2) We remembered “an old method” to estimate area last year.

24 15 12 9 13

Total 73

It is a basic mathematics. The area of red rectangle is 200cm2. Please estimate the total area of green figures using the formula.

Where n=200, W=10cm×20cm = 200cm2

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Ans. 73cm2

The method use dots, therefore it can measure complicated fields, large, small, sloped field, mixed crops, etc. This is an old method, very simple method to estimate area.

The number of dots on the green areas must be proportional to the size of green area in the population. The proportion of sample must be same as that of population. If you distribute sample dots,………….

Then, We found Dot sampling method using

“Google Earth” which is the latest IT.

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What is the method?

For example, please suppose that you distribute 100 sample dots using systematic random sampling on the area (map). Then you go and check what crop is growing at each sample dot. Thus, you can obtain 100 answers from the dots. Then, you can calculate the share by crop. The each share is the estimated share of crop in the area. Finally, the planted area by crops is generated through the formula.

Samplename

Season 1 Season 2

1

2

3

…

…

…

…

n

Category

Image of Questionnare

Category code

Dyke 3

Residential land, ( Inc lude bulding,garden, parking, trees, etc)

4

Road (asphalt) 5

Road (soil) 6

Irigation , River 7

Others 8

Paddy 101

Sweet potato 102

Soybean 103

Vegitable 104

Fruite (Tree) 105

Turf (Lawn) 106

No plant (prepalation) 107

What is Google Earth?

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Anyone can use it.

It is a digital map.

It can zoom up and zoom in. You can see the sights on the maps where you want.

You can do sampling on the map.

You can use it as if it is a sampling list.

It provides us an effective and reliable statistics method, especially land use/planted area survey.

It is a web-site maps which uses the latest Internet Technology.

3. Experiment of the adoption of the method Dot sampling on Excel Sheet

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Longitude/Latitude

140.1241082 140.1246568 140.1252053 140.1257539 140.1263024 140.126851 140.1273995 140.1279481

36.03075098 ,36.03075098,140.1241082

36.03075098,140.12465675

36.03075098,140.1252053

36.03075098,140.12575385

36.03075098,140.1263024

36.03075098,140.12685095

36.03075098,140.1273995

36.03075098,140.12794805

36.03030296 ,36.03030296,140.1241082

36.03030296,140.12465675

36.03030296,140.1252053

36.03030296,140.12575385

36.03030296,140.1263024

36.03030296,140.12685095

36.03030296,140.1273995

36.03030296,140.12794805

36.02985494 ,36.02985494,140.1241082

36.02985494,140.12465675

36.02985494,140.1252053

36.02985494,140.12575385

36.02985494,140.1263024

36.02985494,140.12685095

36.02985494,140.1273995

36.02985494,140.12794805

36.02940692 ,36.02940692,140.1241082

36.02940692,140.12465675

36.02940692,140.1252053

36.02940692,140.12575385

36.02940692,140.1263024

36.02940692,140.12685095

36.02940692,140.1273995

36.02940692,140.12794805

36.0289589 ,36.0289589,140.1241082

36.0289589,140.12465675

36.0289589,140.1252053

36.0289589,140.12575385

36.0289589,140.1263024

36.0289589,140.12685095

36.0289589,140.1273995

36.0289589,140.12794805

36.02851088 ,36.02851088,140.1241082

36.02851088,140.12465675

36.02851088,140.1252053

36.02851088,140.12575385

36.02851088,140.1263024

36.02851088,140.12685095

36.02851088,140.1273995

36.02851088,140.12794805

36.02806286 ,36.02806286,140.1241082

36.02806286,140.12465675

36.02806286,140.1252053

36.02806286,140.12575385

36.02806286,140.1263024

36.02806286,140.12685095

36.02806286,140.1273995

36.02806286,140.12794805

The sample dot points are generated at the cross points of latitude and longitude on a Excel sheet. After that, the points are sent to Google Earth.

A new tool to put sample dots on Google Earth

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“The dot sampling system”(“Yuksel” Program ) was developed for the dot sampling in October 2012. It can put sample dots with name. The file can be uploaded on web site, and also can be sent by e-mail.

Test of Sampling on Google Earth in Tanzania

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You would finish “land cover sample census” in your country on Google Earth in a few days. You would complete “ the number of building survey” on Google Earth in a few days. The method suggests that you could conduct farm households survey using the frames. Furthermore the method suggests you can apply it to the cluster dot sampling method.

Samplename

Season 1 Season 2

1

2

3

…

…

…

…

n

Category

Image of Questionnare

The result of Land Use Survey (Tanzania in January 2012)

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Cultivated land

(pure), 14.0

Dykes, 0.7

may be cultivated land, 3.2

Grass, Wood, Forest,

Mountain, 71.4

River, Lake,, 7.2

Road, 0.9

Residence, Building, etc, 0.3

Cloud, 0.3

Low resolution,

2.0

The results must be reliable.

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

8.0

9.0

10.0

Aru

sha

Dar

es

Sala

am

Do

do

ma

Irin

ga

Kag

era

Kig

om

a

Kili

man

jaro

Lin

di

Man

yara

Mar

a

Mb

eya

Mo

rogo

ro

Mtw

ara

Mw

anza

Pw

ani

Ru

kwa

Ru

vum

a

Shin

yan

ya

Sin

gid

a

Tab

ora

Tan

ga

share of land %

Comparisons between dot estimate and official figures in

Tanzania on the shares by province

Estimate by dot sampling（Eeclude outside lakes ）

Land area (Tanzania)

Target area/ Google Earth

Dot Sampling System

Land use survey

Planted area survey

Crop cutting survey

Socio economics survey

Livestock survey, etc.

Concept of the Dot Sampling System and Master Sampling Frame on Google Earth

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□Dot □ Frame

• This is the concept of the dot sampling system.

• If you use this system, you would carry out speedy not only area survey but also various sampling surveys.

• It seems “Sampling Frame Creator”

• The system could be worked under the Global Strategy.

4. Conclusion (1) We are convinced that the “Dot Sampling Method” to estimate planted area and “Dot Sampling System” to

generate a Master Sampling Frames will play important role to carry out various sampling surveys including listing survey.

(2) We hope that “Dot Sampling Method” and “Dot

Sampling System” are used under the Global Strategy.

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Thank you very much.

Reference

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[Reference ] GLOBAL STRATEGY TO IMPROVE AGRICULTURAL AND RURAL STATICTICS SEPTEMBER 2010 THE WORLD BANK, FAO. ACTION PLAN of the global strategy to improve agricultural and rural statistics. 2012 FAO Estimation of Planted Area using the Dot Sampling Method Kenji Kamikura Senior Statistician, Statistics Department Ministry of Agriculture, Forestry and Fisheries of Japan. (FAO APCAS 24 Document October 2012 ) Improving Statistics for Food Security, Sustainable Agriculture, and Rural Development. An Action Plan for Africa 2011-2015. May 2011. By AfDB, AUC, ECA, FAO. GLOBAL STRATEGY TO IMPROVE AGRICULTURAL AND RURAL STATISTICS A FRAMEWORK FOR CAPACITY DEVELOPMENT AND TECHNICAL ASSISTANCE Naman Keita Manager CountrySTAT Statistics Division Food and Agriculture Organization of the United Nations (FAO) 28 November 2011, Paris. Building & Using Area Sampling Frames for Agricultural Censuses & Surveys Theresa “Terry” Holland USDA National Agricultural Statistics Service. 21 June 2011Montevideo, Uruguay Improving Agricultural Statistics in Tanzania: Results of USDA and FAO-USDA Assessments Theresa “Terry” Holland USDA National Agricultural Statistics Service. 21 June 2012 Kigali, Rwanda Google Earth on the Internet web site