Ethical Considerations
The study was reviewed and approved by the Ethics Committee of Sun Yat-sen University (Institutional Review Board number 054/19; February 28, 2019) and confirmed by Lingnan before the study. Participation in this study was voluntary and all data were made anonymous. We included only those that had provided written or online informed consent. Egos received a compensation of 20 RMB (≈US $3) for each alter recruited, and alters received a compensation of 50 RMB (≈US $7.5) after completing the questionnaire. Compensation was issued through a reward (E-Red Pocket) on WeChat.