Answer:
It is stratified random sampling.
Explanation:
When taking a sample for a survey, it can either be a probability sampling or a non probability sampling.
Probability sampling is a sampling method that helps you know if your sample is a representative of the population or not. This is because you know the probability of each member of the population being part of the sample. In non probability sampling, it is impossible for the researcher to note the probability of each member being part of the sample.
Probability sampling is of many types. This includes simple random sampling, stratified random sampling, cluster sampling, systematic random sampling. However, stratified random sampling, a type of probability sampling allows you to take random samples from every group that make up the population. In stratified random sampling, the population is divided into smaller groups of people who share some major attributes such as age, literacy level, etc. Samples are then taken randomly from each group, also called strata, to make up the main sample for the survey. By doing this, it is ensured that every class of the population is well represented. When the same proportion or number is taken from every group to make up the sample, it is called proportional stratified random sampling but when a larger share comes from certain group(s) for some reasons, it is called non proportional stratified random sampling.
Since in this college, the statistics students collected samples from freshmen, sophomores, juniors and seniors (which are the groups that make up the college) for their survey, the sampling method is Stratified random sampling.
Stratified sampling can also be used in a market survey to study how easily goods are sold during festive seasons. The population can be divided into strata based on what the sellers sell and samples take from all strata. By this, the researcher is confident that his or her sample is a good representative of the market population and is sure to get a good result.