Final answer:
In stratified sampling, the population is divided into groups called strata, and a sample is selected by picking the same number of values from each stratum. This helps ensure that each subgroup of the population is adequately represented in the sample.
Step-by-step explanation:
In the process of stratified sampling, there are several important steps to follow. First, the population is divided into groups called strata. Then, a sample is selected by picking the same number of values from each stratum until the desired sample size is reached. For example, a high school student population can be stratified by year (freshmen, sophomores, juniors, and seniors) and a proportionate simple random sample can be chosen from each stratum.
To choose a stratified sample, each student from each year is numbered, and then simple random sampling is used to select the proportionate numbers of students from each year. The numbers picked from each year represent the students who make up the stratified sample. This helps ensure that each subgroup of the population is adequately represented in the sample.