# SADC Course in Statistics The Swaziland area survey Choice Ginindza.

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SADC Course in Statistics The Swaziland area survey Choice Ginindza

Overview Annual crop-cutting survey Concentrate on the measurement of areas –under each crop Forms for collection What happens to the data –after they have been collected

Each enumerator has a copy of this guide

Holding layout sketch plan Field 1 Maize Field 2 60% maize, 40% pumpkins Field 4 maize Field 3 beans

Symbols for the sketch plan

Field area measurements 1 2 2 0 10 5 2 0 1 125 50 27.5 0.85 113 100 0.25 112 60 139 40

Area in each field 01 Maize 100% 113 0.85 02 M 60% Pk 40% 112 139 03 Beans 100% 131 0.53 04 Maize 100% 113 0.98

Total crop area 0.15 1.83 0.61 0.53

Other information is also recorded

Plus household information

What happens next? 75 staff collect these area data between November and January each year The completed forms are sent to me in HQ –there are about 2000 forms each year –it is one form per household, unless a household has more than 12 fields The forms are checked for consistency –before being sent for data entry They are then sent for data entry –By the end of January

Then – the data are entered Special software is used for the data entry –It is called CSPRO –and is designed specially for data entry A headquarters' staff member –has programmed CSPRO –to make the data entry screen –the same as the data entry form There are 7 staff –in the Government data entry team –and I add 2 of my staff just for this work It takes about 2 weeks

Checking the data once entered The resulting computer files –are returned to me I first look at them in an editor –it is called OX-edit and is just like Notepad –that is on every computer I use the editor to look for shifts –in the data from CSPRO –one character missing can make the transfer –to Excel or a statistics package very odd That checking just takes an hour perhaps

The data now Then I open the data in SPSS –That is a commonly used statistics package They look the same in Excel – –as shown on the next slide There are now 3945 records, –each one is a crop within a household. Plus the household information

Crop area information

Household information

Checking in SPSS I check the data in SPSS –That typically takes one day I also have the paper records available –And check odd values against them I correct in SPSS (and Ox-Edit) Sometimes records are returned –to the data entry people –and there is a further round Typically we find problems with 10 to 30 records

Analysis Now I analyse the data using SPSS That takes perhaps 1 day The most important is maize, –so that is done first. I get results from each Enumeration area And then total them for each district I compare with the previous year –as another check I then export the summaries from SPSS to Excel

Results Here is the sort of table I get.

Reporting This information is then sent –to our Meteorological Service They have to be there by the end of February The met service estimates yields And these estimates are multiplied –by these areas To give the estimated production

Publishing The estimates are then in a monthly –agroclimatic bulletin Which is part of our NEW system –NEW = National Early Warning to provide the food-balance sheet –for the current year Later we produce our own report –once we have the yields as well

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