I remember reading a paper where the Difference-in-Differences was a bit special, but I had forgotten the details. My recollection was

  • Two time periods, specifically one time period before treatment and one time period after treatment.
  • The "treatment" was such that all firms had to comply with a certain share of a variable X.
  • The treatment group consisted of firms with very low (or zero) share of X before the treatment, and
  • The control group consisted of firms with a share already close to the required share of X before the treatment.

The idea was that the treatment group received most of the shock, while the control group was little affected.

Do you know a paper that uses such a framework?


1 Answer 1


Take a look at Ch 5 of Mastering Metrics (Angrist and Pischke) or their earlier "Mostly harmless econometrics".

  • 2
    $\begingroup$ This does not seem to answer the question, which is looking for the title of a paper. $\endgroup$
    – Giskard
    Aug 14, 2020 at 18:52
  • $\begingroup$ My reading is that the OP is asking for examples that need not appear in papers as opposed to books. The book of course contains references to papers. $\endgroup$ Aug 15, 2020 at 19:04
  • $\begingroup$ @LutzHendricks Thanks. I know those books that tend to present the classic case (where only the treatment group is treated and not all the subjects). I'm really looking for papers here. $\endgroup$
    – emeryville
    Aug 20, 2020 at 10:40
  • $\begingroup$ The chapter in Mostly Harmless Econometrics cites a few papers: Card, David, and Alan Krueger (1994): “Minimum Wages and Employment: A Case Study of the Fast Food Industry in New Jersey and Pennsylvania.” The American Economic Review 84, 772-84. —— (2000): “Minimum Wages and Employment: A Case Study of the Fast-Food Industry in New Jersey and Pennsylvania: Reply.” The American Economic Review 90, 1397-420. There also the papers by Pischke, Autor 2003, Card 1992. Perhaps I misunderstand what you are looking for, but these seem to fit the bill. $\endgroup$ Aug 20, 2020 at 20:01
  • $\begingroup$ @LutzHendricks I am aware of this paper. See this thread. In Card-Krueger only New Jersey raised the state minimum, not eastern Pennsylvania. Please read my "treatment" and the difference between my treatment and control groups. $\endgroup$
    – emeryville
    Aug 22, 2020 at 7:21

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