stata 用findit psmatch2 安装
显示:
connection timed out -- see help r(2) for troubleshooting
http://fmwww.bc.edu/RePEc/bocode/p/ either
1) is not a valid URL, or
2) could not be contacted, or
3) is not a Stata download site (has no stata.toc file).
各位大佬,该怎么破