1. Multistage Sampling
Module 3
Session 9

2. Session Objectives To introduce Multistage sampling
To help participants appreciate when to apply multi-stage sampling

3. Multi-Stage Sampling Design
Most commonly used sampling design in practice
Involves more than one stage of sampling and/or a combination of two or more sampling designs

4. Why apply multi-stage sampling
Structure of the population
Size of population (large)
Fund available for the survey

5. Examples of multi-stage sampling
A Systematic sample of households within Enumeration Areas (EAs) within Districts
Districts – Strata – 1st Stage
EAs- Clusters- 2nd Stage
Households -3rd Stage
Within each District take a sample of EAs
Within each EAs, take a sample of h’holds
Within each household, sample 2 individuals

6. Cont’d
Determine from students at a university their opinion of the university.
Stratify students according to their Faculty (Science, etc.) (strata 1st )
Take simple random sample of courses in each of these Faculties (clusters 2nd )
From each course take a random sample of students.

7. Sampling and Analysis issues using the Paddy Game
Module 3
Session 9(b)

8. Session Objectives
To introduce basic sampling concepts using the Paddy game
To demonstrate how to select a sample from a population
To demonstrate how population values can be estimated from samples

9. What is Paddy?
Paddy is a game that has been developed to demonstrate how to design and analyse survey data
The game uses an example of a survey of rice production
Open the paddy game on your computer by clicking on the PADDY icon.

10. Background Information
In a small district there are:
10 villages
With a total of 160 farmers
Each with one field in which to grow rice
A census has been undertaken and the acreage cultivated by each farmer is known.

11. Number of Farmers & Acreage - by Village

12. Aim of the Survey
The main aim of the survey is to estimate the mean yield of rice per hectare and hence the total production of rice in the district
In order to do this you will carry out a crop cutting survey. This is a survey where you visit fields, harvest the crop from one or more plots and measure the yield
A further objective is to investigate the use of fertiliser and varieties by the farmers

13. Resources
The resources available allow you to visit and collect information from 30 plots.
A plot covers an area of 1/80th of an acre.
Yield from each plot harvested is then measured in bushels per acre.

14. Resources
Transport costs allow your survey team to visit a maximum of 5 villages, although you might decide to visit less than 5.
These costs dictate that the survey should use a multistage sampling design

15. Resources The game gives you the possibility of three levels: Villages
Farmers within Village
Plots within farmers.

16. Pilot Run
We begin with a pilot run to give you familiarity with the Paddy game
The Paddy game has been installed on your computers
The sampling scheme suggested is the following:
Select 2 villages using simple random sampling
From each village select 3 fields, again with simple random sampling
From each field, select 1 plot at random for harvesting

17. Designing the Sampling scheme

18. Designing the Sampling Scheme - Selecting fields in village 6 -

19. Designing the Sampling Scheme - Selecting fields in village 7 -

20. The Sample

21. Probability Proportional to Size (PPS) Sampling using the Paddy Game
Module 3
Session 9(c)

22. Session Objectives
To demonstrate how to select a sample from a population using PPS
To demonstrate how population values can be estimated from samples

23. Pilot Run Suppose the sampling scheme suggested is the following:
Select 2 villages using PPS sampling where the sample depends on the number of farmers in the village
From each village select 3 fields, with simple random sampling
From each field, select 1 plot at random for harvesting

24. Designing the Sampling scheme

25. Designing the Sampling scheme

26. Selecting fields for Village 6

27. Selecting fields for Village 7

28. The Sample