基金项目: | The authors would like to give special thanks to General Statistical Office(GSO) for using the dataset of VHLSS 2004 and 2008. A warmest thank to Joseph Arbiol and Kyle for helping the authors by proofreading this paper at the earlier versions. Their efforts are highly appreciated. The authors arealso gratefully to the participants who provided comments and questions for this paper at the 2nd ICBER in Langkawi Kedah, Malaysia from March 14th-16th, 2011. |