Randomization and masking
RECRUITMENT
First, a random number table was generated by a researcher who was not involved in the intervention using IBM SPSS Statistics version 26.0. Each participant was assigned a unique number in the order of enrolling in the study. Then, the unique number of participants was separated from other information and sent to the researcher who generated the random number table, and this researcher, using the random number table, assigned participants to intervention or control condition. In this process, this researcher will not be exposed to other personal information of participants. Even though the recruitment of participants is divided into 2 periods, because the unified random number table generated in advance is used, the randomization process was guaranteed to be single-random.A total of 144 participants who signed the informed consent form were stratified by gender assigned at birth (male/female) and then randomly allocated (1:1) to the experimental or control condition. Participants were masked to their group assignment, although they were informed of the existence of another group. The unified numbering procedure for all participants was used to minimize the possibility of participants knowing their groups according to the assigned number. Due to the nature of the present study, masking the study group facilitators was impossible. Nevertheless, we minimized the experimenter effect by having 3 group facilitators assigned to the experimental and control conditions, respectively.