黃河泉 发表于 2019-6-9 08:21 
试试
谢谢老师,不过我试了以后还是不行。直接用你的代码或者是我的数据都不行~stata显示“file fracreg.txt could not be opened”。看了stata显示的error原因是 “ This file, although found, failed to open properly. This error is unlikely to occur. You will have to review your operating system's manual to determine why it occurred.”看不懂应该怎么解决。老师您能帮忙看下怎么解决吗?谢谢老师!!!