3 Data gathering and processing
3.2 Sampling

Many steps of planning a survey rely on a good understanding of information user needs and good knowledge of the steps to follow to carry the survey. One of the first steps for which a good knowledge of mathematical statistics is also needed is sampling, which is the method used to select a subset of units from the target population. There are many methods possible and the chosen method will have a direct impact on the accuracy of the statistics that are being produced. For this reason, it is important to understand the differences between the different sampling designs. They can be split into two types: probability sampling and non-probability sampling. But first, let’s see what elements must be taken into account to choose the sampling design that is the most appropriate in a given context.