openintro (version 1.7.1)

textbooks: Textbook data for UCLA Bookstore and Amazon

Description

A random sample was taken of nearly 10% of UCLA courses. The most expensive textbook for each course was identified, and its new price at the UCLA Bookstore and on Amazon.com were recorded.

Usage

data(textbooks)

Format

A data frame with 73 observations on the following 7 variables.

deptAbbr

Course department (abbreviated).

course

Course number.

ibsn

Book ISBN.

uclaNew

New price at the UCLA Bookstore.

amazNew

New price on Amazon.com.

more

Whether additional books were required for the course (Y means "yes, additional books were required").

diff

The UCLA Bookstore price minus the Amazon.com price for each book.

Details

The sample represents only courses where textbooks were listed online through UCLA Bookstore's website. The most expensive textbook was selected based on the UCLA Bookstore price, which may insert bias into the data; for this reason, it may be beneficial to analyze only the data where more is "N".

References

See Section 5.1 of the Open Intro Statistics textbook: http://www.openintro.org/

Examples

# NOT RUN {
data(textbooks)
#===> an improper analysis <===#
boxPlot(textbooks$uclaNew, xlim=c(0.5,2.5))
boxPlot(textbooks$amazNew, add=2)
axis(1, at=1:2, labels=c('UCLA Bookstore', 'Amazon'))
t.test(textbooks$uclaNew, textbooks$amazNew)

#===> a reasonable analysis <===#
#     the differences are moderately skewed
#     the sample size is sufficiently large to justify t test
histPlot(textbooks$diff)
t.test(textbooks$diff)
# }