Event study in stata with reghdfe

[Swarup8289]

For this code:

use "https://raw.githubusercontent.com/LOST-STATS/LOST-STATS.github.io/master/Model_Estimation/Data/Event_Study_DiD/bacon_example.dta", clear

• create the lag/lead for treated states

• fill in control obs with 0

• This allows for the interaction between treat and time_to_treat to occur for each state.

• Otherwise, there may be some NAs and the estimations will be off.
  g time_to_treat = year - _nfd
  replace time_to_treat = 0 if missing(_nfd)

• this will determine the difference

• btw controls and treated states
  g treat = !missing(_nfd)

• Stata won't allow factors with negative values, so let's shift

• time-to-treat to start at 0, keeping track of where the true -1 is
  summ time_to_treat
  g shifted_ttt = time_to_treat - r(min)
  summ shifted_ttt if time_to_treat == -1
  local true_neg1 = r(mean)

• Regress on our interaction terms with FEs for group and year,

• clustering at the group (state) level

• use ib# to specify our reference group
  reghdfe asmrs ib`true_neg1'.shifted_ttt pcinc asmrh cases, a(stfips year) vce(cluster stfips)

--> For the regression in the last line, i do not see the interaction term: treat## ib`true_neg1'.shifted_ttt. Is it a typo? Or is there a logic behind not including the interaction with "treat" variable?

Thank you guys!