Stratified sampling is a sampling technique where the researcher divides or 'stratifies' the target group into sections, each representing a key group (or characteristic) that should be present in the final sample.For example, if a class has 20 students, 18 male and 2 female, and a researcher wanted a sample of 10, the sample would consist of 9 randomly chosen males and 1 randomly chosen female, to represent this population.