就是普通的reg，只是需模型需要设定一下，看伍德里奇的导论。

自己下载diff命令
findit diff


help diff
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Title

    diff --       Difference in differences estimation


Syntax

        diff outcome_var [if] [in] [weight] ,[ options]


Description

    diff performs several difference in differences (diff-in-diff) treatment effect
    estimations of a given outcome variable from a pooled baseline and follow up dataset:
    Single Diff-in-Diff, Diff-in-Diff accounting for covariates, Kernel Propensity Score
    Matching diff-in-diff, and the Quantile Diff-in-Diff.  diff is also suitable for
    estimating repeated cross sections diff-in-diff (including the kernel option) and the
    triple difference analysis.

安装不了diff命令，还有coefplot，intall命令错误，是什么问题呀。盗版的stata吗？

那是你自己网络问题

https://ideas.repec.org/c/boc/bocode/s457083.html
你可以直接下载，拷贝到相应目录中https://bbs.pinggu.org/thread-2420580-1-1.html

reg y treat period treat*period x1 x2 ... xN ,r