Different sampling methods are usually used depending on the type of survey that is to be carried out, and each of these methods has its own unique advantages that contribute to a reliable and valid research. Examples include:
1. Random sampling. Each individual is chosen entirely by chance and so the likelihood of bias is reduced.
2. Cluster sampling. The entire population is divided into groups or clusters and a random sample of these clusters is selected. All observations in the selected cluster largely represent the rest of the population and this yields a fairly accurate and valid analysis.
3. Quota sampling. When a probability sample cannot be obtained,this method of sampling helps create an accurate sample of the population thereby producing credible results.
