<p><font face="Verdana" size="2">帮忙寻下这篇吧Ham J and R Lalonde.(1996)"The Effect of Sample Selection and Initital Conditions in Duration Models:Evidence from Experimental Data on Training",Econometrica,64:1.我找到了，不过要收费，无奈。如果谁有的话希望能发给我，万分感谢！</font></p><p><font face="Verdana" size="2">我的邮箱是<a href="mailto:tianjfield@163.com">tianjfield@163.com</a></font></p>