Learning in formal groups over time: a problem of power?

Since the subsets of the class (A and B) are composed of only approximately 40 students in curriculum year 2, the lack of power could explain why differences between the control group and the subsets of the classes did not reach significance in year 2. Therefore, the intervention groups were combined in the analyses of the modules in the second year. Again, the control group (C) is compared to the intervention groups (A+B) and the non-randomised student group (nR).*signifies p-value≤0.05.