Funding for this research was provided by:
National Natural Science Foundation of China (71704006)
Article History
Received: 27 May 2020
Accepted: 28 September 2020
First Online: 6 October 2020
Ethics approval and consent to participate
: The CHARLS surveys were approved by the Ethical Review Committee of Peking University. The data used in this study are released data by CHARLS for public use. Permissions were acquired to access the data used in our research, which were granted by CHARLS team.
: Not applicable.
: All the authors have no financial or any other kind of personal conflicts with this manuscript.