RCP method
A total sample size of 480 observations, were obtained by sampling 3 level-2 units (PHD) in the control group, 3 level-2 units (PHD) in I only group, 3 level-2 units (PHD) in the E only group, and 3 level-2 units (PHD) in the E+I group. Finally, 40 level-1 units (individuals with repeated measurements) were obtained from each level-2 unit (PHD). This sample achieves >90% power to detect a three-way interaction among the subject-specific slopes of at least 3.0. A test based on a mixed-model analysis assuming random slopes will be used. This test will be conducted at a significance level of 0.05.