The average purchase size from your online sales site is $17, 200. The customer experience team
believes a certain adjustment of the website will increase sales. A pilot study on a few hundred
customers showed an increase in average purchase size of $1.47, with a significance level of
p=0.1.
The team runs a larger study, of a few thousand customers. The second study shows an
increased average purchase size of $0.74, with a significance level of 0.03. What is your
assessment of this study?

A.
The change in purchase size is not practically important,and the good p-value of the second
study is probably a result of the large study size.

B.
The change in purchase size is small,but may aggregate up to a large increase in profits over
the entire customer base.

C.
The difference in the change in purchase size between the two studies is troubling; The team
should run another,larger study.

D.
The p-value of the second study shows a statistically significant change in purchase size. The
new website is an improvement.