Published on in Vol 22, No 8 (2020): August
Preprints (earlier versions) of this paper are
available at
https://www.medrxiv.org/content/10.1101/2020.05.31.20118414v1, first published
.
1 College of Economics and Management, China-Africa International Business School, Zhejiang Normal University, Jinhua, China
2 Cofintelligence Financial Technology Ltd., Shanghai, China
3 Cofintelligence Financial Technology Ltd., Hong Kong, China (Hong Kong)