Funding for this research was provided by:
the MOE Layout Foundation of Humanities and Social Sciences (20YJAZH140)
Received: 14 January 2020
Accepted: 15 September 2020
First Online: 29 September 2020
Ethics approval and consent to participate
: The data used in this manuscript were from a large national social survey (CLASS). All the participants provide written consent prior to their participation in the survey, and the research was approved by the Academic Committee of the School of Statistics of Renmin University of China, but the ethics number has not been publicly released.
: Not applicable.
: The authors declare that they have no competing interests.