Question

Jane Doe et al. randomly assigned students in an economics class to lecture sessions in which taking notes on laptops was permitted, or to lecture sections from which laptops were banned. They tested for differences in mean final exam score between these two treatments, with three separate analyses for students with GPAs in the bottom, middle, or top third of the class GPA distribution.

Their results are summarized in the table below, which shows the differences in mean final exam score between the two treatments (laptops permitted minus laptops banned) for each GPA group. Differences with an asterisk are statistically significantly different from zero at the 0.05 level.

Students with bottom-third GPA	Students with middle-third GPA	Students with upper-third GPA
-0.10	-0.17*	-0.25*

Doe et al. concluded that students with the highest GPAs were harmed more by laptop usage than were students with intermediate or low GPAs, writing "We might have expected [the students with the highest GPAs] to have used their laptops prudently. Instead, they became technology’s biggest victims."

Explain why this conclusion is not justified by statistical analyses presented. Suggest what should have been done instead to test for differences in the effect of laptop usage on students with different GPAs.

Answer 1

The conclusion is not justified as student with higher GPAs score more marks and getting a difference of -0.25 is completely possible as we know that less students score high marks and also their scores usually varies more.So it's natural to get a higher difference and we cannot conclude that higher GPA students were harmed more.

It is also possible that the students who attended lecture with laptops permitted might have improved from their previous scores

and the test and results that we have shows difference between the scores of writing and laptop group it does not tell anything about what were  the previous scores of students who used laptop.

Please upvote If I am able to help you.

Thanks