What is post*treat value in the year of event? Regarding Difference-in-Difference, from this paper of Dasgupta,2019, I am wondering if they use the data of the observations on the event year.
I asked this question because in their paper, they did not mention clearly whether they use the data on event year in their study.
What they said from section 3.1 is

Figure 1 plots the mean of the mean change in asset growth of treated
firms and control firms in the same industry, 2 years before and 5
years after the adoption of a leniency law in a country. Thus, the
control firms are all firms in the same industry in countries that had
not passed a leniency law in the 7 years surrounding the event date.

I am wondering why they say "7 years surrounding the event"? Whether "surrounding the event date" includes the event date?
For clarifying the question, for example:
If Korea passed the law in 1997, so the treatment including Korean firms in 1995,1996,1997,1998,1999,2000,2001 and the Korean firms in 1997,1998,1999,2000,2001 will receive the value of 1 (post x treatment)
or
the treatment including Korean firms in 1995,1996,1998,1999,2000,2001,2002 and the Korean firms in 1998,1999,2000,2001,2002 will receive the value of 1 (post x treatment)
or another option as one answer below

So, Treat x Post of Korean firms in 1995,1996 will receive the values
of 0 but Korean firms in 1997,1998,1999,2000,2001,2002 will receive
the value of 1. That is why I said 8 years in total. "7 years
surrounding" here means 2 years before and 5 years after and the event
year, totally 8 years.

 A: First, clarifying the definition of "treatment" and "post":

*

*Treatment is the units that were treated, independent of time.


*Post is the year when treatment began.


*Treat x Post : is your effect and includes treated firms in treated years.
Let's say t=0 is the year of the event and t>0 are posterior years.
So the treatment includes only treated firms in all years. Post includes all firms only in treated years when t>=0. So, in your case, it would be the first case

If Korea passed the law in 1997, so the treatment including Korean
firms in 1995,1996,1997,1998,1999,2000,2001 and the Korean firms in
1997,1998,1999,2000,2001 will receive the value of 1 (post x
treatment)

But I also learnt something from this paper. It seems that, he used 8 years for a treatment in total. Let's say, if Korea passed the law in 1997.
So, Treat x Post of Korean firms in 1995,1996 will receive the values of 0 but Korean firms in 1997,1998,1999,2000,2001,2002 will receive the value of 1. That is why I said 8 years in total.
"7 years surrounding" here means 2 years before and 5 years after and the event year, totally 8 years.
But it is still ambiguous to me if it is the case (8 years)
