I am using data from a controlled experiment with different timing of treatment implementation across individuals in the treated group. I can date treated observations with time distance to the implementation dates; However, how can I make a trend plot for control group? In particular, how to date the trend for control individuals?
1 Answer
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1 I found that the good way to do it is using "stacked cohort" diff-in-diff, where you create a dataset that covers a time window for each event, and then stack up the datasets into one. One example is in Gormley and Matsa (2011).
- $\begingroup$ Actually, it is not correct to do this, because Post_t is not well-defined. We cannot test the parallel trend assumption in this case. $\endgroup$Hong You– Hong You2020-06-18 14:51:38 +00:00Commented Jun 18, 2020 at 14:51