Text and Data Mining valid from 2018-04-03
Received: 20 July 2017
Accepted: 6 March 2018
First Online: 3 April 2018
: Xin Xie: Department of Economics and Finance, College of Business and Technology, East Tennessee State University, Johnson City, TN 37614, USA. Nianyang Wang: Department of Preventive Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA. Ying Liu: Department of Biostatistics and Epidemiology, College of Public Health, East Tennessee State University, Johnson City, TN 37614, USA.
: The current study was approved by the Institution Review Board (IRB) of East Tennessee State University. There was IRB exemption due to secondary data analysis of public available data.
: Our manuscript does not contain any individual person’s data in any form.
: The authors declare that they have no conflict of interest.