Allbookstores

Allbookstores.com has a used textbook division. It buys its books in bulk from used book buyers who set up kiosks on college campuses during final exams, and it sells the used textbooks to students who log on to the allbookstores.com website via a secured credit card transaction. The used texts are then sent by United Parcel Service to the student.

The company has conducted a survey of used book buying by college students each year for the past four years. In each survey, 1,000 randomly selected college students have been asked to indicate whether they bought a used textbook in the previous year. The results are as follows:

What are the sample size implications of these data?