Hello everybody,

I am trying to run an event study model, i.e. I want seperate coefficients of a continous treatment for each period relative to the base period when the event takes place.
Unfortunately, I cannot figure out how to make Stata omit the base period when using the factor variable notation.

If you are aware of a post that already clarified the issue, please let me know - I did not find it when searching statalist.
Here is a little example code:

Code:
sysuse xtline1.dta, clear

gen drnks = .
replace drnks = 10 if person==1
replace drnks = 1 if person==2
replace drnks = 25 if person==3

keep if inrange(day,15520,15530)

// Event on 4th of july = 15525
reg calories i.person i.day io15525.day#c.drnks , nocons
In the example person is the id variable, day is the time variable and drnks is the treatment and calories is the outcome. The event take place on the 4th of July, which is equal to 15525.
I would like to get a seperate coefficient for drnks for each day, that gives me the effect of drnks on calories relative to the event date 15525. In addition I would like to include person and time fixed effects.

Here's the output, where there is a coefficient for 15525, although I thought this level of day should be omitted:

Array

How can I make Stata omit the coefficient for the event date?

Best regards
Boris