CEVAP:

In stratified sampling method, the target population is divided into homogenous subgroups which are called strata. Each subgroup is called stratum. Then a probability sampling method such as simple random sampling method is applied for each stratum to take a sample from the population. The strata must be mutually exclusive and exhaustive. This means that each unit of the population must be assigned to only one stratum. Strata should be determined based on available characteristics that they are related to the outcome of the survey or research. When a population can be clearly divided into homogenous groups based on some characteristic, we can use stratified random sampling.