Study design
For the purposes of this case study, and to ensure that formulae do not become too complicated, we shall ignore stratification. We shall also assume two scenarios during the course of this case study, firstly that dip-tank areas are selected at random with equal probability, and, secondly that they are selected with probability proportional to their size.
Dip-tank areas were used as clusters in the sampling frame because they form an important feature within the livestock administrative structure for Swaziland. Indeed, the majority of the government's livestock departmental field staff is based in dip-tank areas.
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Taking into consideration cost, human resource and time, it was decided to sample a total of 60 dip-tank areas in each of the four regions, i.e. a total of 240 from the 430 dip tanks in the country. The table shows the numbers of dip-tank areas within the sub-regions in the Hhohho region and the numbers of dip-tank areas sampled. |
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