Problem 12

Given information

Given: 

A group of test subjects is divided into twelve groups; then four of the groups are chosen at random.

Step-by-step explanation

In statistics, sampling is the process of selecting a finite number of individuals or observations from a population. A sample is representation of the population from which it is drawn. 

Sampling is done because it is not possible to work with the entire population as population sizes are large, so a subset of the population that is a sample is drawn and the analysis is done with it and interpretation regarding the population are done based on the sample.

The sampling methods stated in this problem are:

1. Simple random sampling - It is the process in which a unit is randomly selected from the population and every unit has an equal probability of getting selected.
2. Systematic sampling - It is the process in which a starting point is randomly selected and then every unit is selected from the population.
3. Stratified sampling - It is method in which the population is divided into strata's and then a simple random sample is drawn from each strata.
4. Cluster sampling - It is the method in which population is divided into clusters, then some clusters are randomly selected. The selected clusters are then completely enumerated.
5. Convenience sampling - It is a non-probability sampling. It is the method in which samples are collected from easily available sources. 

In the given question, the researcher divides the test subjects into twelve groups and then selects four groups randomly. So, here the population is divided into 12 groups that is 12 clusters and from those 12 groups, 4 groups are randomly selected. Thus, the sampling method in this question is representing cluster sampling.

So, cluster sampling was used as method of sampling for drawing the sample.