Submitted on: 22 March 2015.
Revised on: 12 April 2015.
Accepted on: 05 May 2015.
___________________JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH
http://reply.papertrans.cn/2/167/16672/16672-12.png
http://reply.papertrans.cn/2/167/16672/16672-13.png
Submitted on: 16 November 2004.
Revised on: 27 February 2005.
Accepted on: 18 March 2005.
___________________JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH
http://reply.papertrans.cn/2/167/16672/16672-15.png
http://reply.papertrans.cn/2/167/16672/16672-16.png
Submitted on: 28 February 2000.
Revised on: 06 May 2000.
Accepted on: 22 June 2000.
___________________JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH
http://reply.papertrans.cn/2/167/16672/16672-18.png
Submitted on: 20 September 2011.
Revised on: 04 November 2011.
Accepted on: 21 November 2011.
___________________JOURNAL OF EPIDEMIOLOGY AND COMMUNITY HEALTH
http://reply.papertrans.cn/2/167/16672/16672-20.png