Chapter 4.1, Problem 18E

To determine

To describe how to select a stratified random sample of approximately $100$ students and explain your choice of strata and also explain why stratified random sampling might be preferred in this context.

Explanation of Solution

Divide all the undergraduate students of the University into strata(groups) so that the students of every strata have a common aspect. For example, let them be divided into $5$ strata of different departments such as B.Com, BA Economics, B.Sc Mathematics, BA English, BA Fine Arts (assuming that the university is providing these $5$ undergraduate courses) and then randomly select the proportionate number of students from each strata so that total students from all strata are $100$ . Now, out of our selected sample of $100$ students, find out the proportion of students who regularly park a car on campus. We call this as a sample proportion.

We used the stratified random sampling so that our sample proportion represents the population proportion as we included all the undergraduate students of different courses or departments proportionately in our selected sample.

Thus, Stratified random sampling is applied because the population (all the undergraduate students of the University) contains homogeneous groups (courses) and thus, it is required to include students of each course in the sample for it to represent the population.