2.3. Randomization and Masking
Four random classrooms were selected in each school (Medicine, Pharmacy and Communication): twelve classes in all. Of the four selected classrooms in each school, two were assigned to each group (CG and IG), according to the following sequence: first class: IG; second class: CG; third class: IG; and fourth class: CG. In this way, all students in the same class were assigned to the CG or the IG by probability single-stage cluster sampling.Due to the nature of the study, the students could not be blinded. However, the statistical analysis of the data was performed by a person who remained blinded throughout the study. In addition, each participant only had access to one version of the application (CG: ‘non-feedback’ e-12HR version; IG; ‘feedback’ e-12HR version). This was possible by assigning personal alphanumeric codes (mentioned in the previous section).The allocation sequence is detailed in 