Question

A 9th grade class is chosen for an experiment. A random half of the students receive specialized one-on-one tutoring in the classroom twice a week. The other half of the students work in study groups in the same classroom as the one-on-one students. The experiment shows that test scores increased at the same rate for both the experimental and control conditions. This is surprising, given that almost every other study of this specialized training showed dramatic improvements in the treatment group. What might be going on in this experiment?

Answer 1

The treatment group was not separate enough from the control group

Answer 2

One of the problems that this experiment might have is that the environment is not properly controlled. Both sets of students are working in the same classroom. This means that the students who are working in groups might be able to hear the tutors who are dealing with the students in a personalized way. Therefore, the groups would show no significant difference because they are both benefitting from the same knowledge.