Randomization and blinding
One of the 3 intervention groups was assigned to each participant. Based on stratified block randomization of six, an Excel program generated the randomization assignment. An assistant who was not involved in the study handled the participant allocation assignments in sealed envelopes and arranged them sequentially. Each envelope was opened right before the intervention was performed. The operators were not blinded to the intervention groups, but all participants, parents, and the evaluators were blinded.