When each member of the population has a known probability, then it is called probability sampling. The examples of probability sampling are simple random sampling, stratified random sampling, cluster sampling. A cluster is a collection of units in nature. If the probability of selection of a unit from a population is considered equal, the probability is called simple random sampling. In stratified random sampling the population is divided into two or more homogeneous groups and sample is chosen from these groups. The sampling in which personal judgment determines that which unit of the population are selected is called non probability sampling. Moreover, quota sampling, purposive sampling are the examples of non probability sampling.

It is a method for choosing a sample from a population in such a way that all possible samples have a specified probability of beeing chosen

Give examples of research questions that can be addressed using any two probability sampling designs. In each case, you should provide a rationale for your answer.