SADC Course in Statistics Sampling design using the Paddy game (Sessions 15&16)

To put your footer here go to View > Header and Footer 2 Learning Objectives By the end of these sessions, you will be able to utilise skills in designing your own sampling scheme to address given objectives collect data, analyse and present the results appropriately to demonstrate your key findings

To put your footer here go to View > Header and Footer 3 Paddy demonstration: Aims To introduce the Paddy game and show how it may be used to select a multi-stage sample To illustrate, via a small example, how population values can be estimated from sample values Note: a separate handout sets out the aims of the paddy exercise and tasks that you are expected to carry out

To put your footer here go to View > Header and Footer 4 Paddy is a game that has been developed to provide practice on how a sampling design may be developed and the data analysed, once collected The game uses an example of a survey of rice production Open the Paddy game on your computer by clicking on the PADDY icon What is the Paddy Game?

To put your footer here go to View > Header and Footer 5 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. Background information

To put your footer here go to View > Header and Footer 6 Farmer numbers and their acreages

To put your footer here go to View > Header and Footer 7 To estimate the mean yield of rice per hectare and hence the total production of rice in the district to investigate the use of fertilisers and improved varieties by the farmers to study the relationship between these factors (fertiliser, variety) and the yield of rice. Paddy survey objectives

To put your footer here go to View > Header and Footer 8 In order to address the objectives, 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 plot covers an area of 1/80 th of an acre. The resources available allow you to visit and collect information from 30 plots. Yield from each harvested plot is then measured in bushels per acre. Crop-cutting survey process

To put your footer here go to View > Header and Footer 9 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 –Village as primary sampling unit –Farmers field within village as the secondary unit –Plot within field as the final stage unit Resources

To put your footer here go to View > Header and Footer 10 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

To put your footer here go to View > Header and Footer 11 Designing the Sampling scheme

To put your footer here go to View > Header and Footer 12 Designing the Sampling Scheme - Selecting fields in village 6 -

To put your footer here go to View > Header and Footer 13 Designing the Sampling Scheme - Selecting fields in village 7 -

To put your footer here go to View > Header and Footer 14 The Sample

To put your footer here go to View > Header and Footer 15 The Sample in Excel

To put your footer here go to View > Header and Footer 16 Computing population Estimates

To put your footer here go to View > Header and Footer 17 Practise playing the Paddy Game Now practise playing the paddy game yourself using a different sampling scheme to that presented in the previous slide The aim here is merely to give you practice – it does not matter that the scheme is not suitable for the actual study You will have 15 minutes for this activity We will then demonstrate how the computer version can be used to draw a PPS sample

To put your footer here go to View > Header and Footer 18 Paddy Game with PPS sampling 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

To put your footer here go to View > Header and Footer 19 Designing the Sampling scheme

To put your footer here go to View > Header and Footer 20 Designing the Sampling scheme

To put your footer here go to View > Header and Footer 21 Selecting fields for Village 6

To put your footer here go to View > Header and Footer 22 Selecting fields for Village 7

To put your footer here go to View > Header and Footer 23 The Sample

To put your footer here go to View > Header and Footer 24 Computing population Estimates

To put your footer here go to View > Header and Footer 25 Now practise drawing a PPS sample. Also read the more detailed handout regarding your tasks for the next two practical sessions…