Question

This is an introduction to social science research methods course:

Imagine you’re planning to estimate the price of the average book at your college bookstore.

The bookstore carries 13,000 titles, but you plan to sample only 200 books.

You will select a sample of 200 books, record the price of each book, and use the average of the 200 books to estimate the average price of the 13,000 titles in the bookstore.

Assume that the bookstore can give you access to a database that lists all 13,000 titles that it carries.

Based on this information, clearly answer the following questions?

How might you collect a cluster sample?

How might you collect a quota sample?

Answer 1

Quota Sampling:

This is a Non Probabilistic way of Samping Plan that divides the population into mutually exclusive subgroups and then the investigator decides how many samples to pick from each segment.

In our bookstore set up, we can create mutually exclusive groupings based on subjects such as Physics,Mathematics,Statistics,History etc. then we can pick sample points from each segment say, 10 from Physics, 15 from Mathematics etc. We can even divide into subgroups of Social Sciences, Sciences and pick as 150 from science and 50 from Social Sciences.

Cluster Sampling:

This sampling plan aims to divide the data points into naturally forming clusters and then take the entire cluster as a part of the sample. These clusters are mutually homogenous but internally heterogenous.

Since the bookstore already has shelves, we can call these shelves as subgroups and pick a few subgroups to create our sample.