Left window of zero returns an error

[Constantino-Carreto-Romero]

Per comment #178 (comment)
When running

use example31, clear
xtevent y, w(0 3) pol(z) impute(stag)

we got the following error message.

[Constantino-Carreto-Romero]

@jorpppp
The error arose because the definition of some temporary variables was missing. We had defined them in the section code that generates the pre-event time dummies variables, but since in the case of left window = 0 that section code is never executed, we must also define the temporary variables in the section code that generates the post-event time dummies variables. Besides, the ordering of the left endpoint needed some adjustment to not assume that there is always at least one pre-event time dummy variable.

Bug fixed in 4c3fa88 and fb9f1b5

After, when running:

use example31, clear
xtevent y, w(0 3) pol(z) impute(stag) savek(aa)

I get the following outcome and the event-time dummies variables are properly ordered.

[jorpppp]

Thanks @Constantino-Carreto-Romero. I'm looking into the fact that plotting is not working now:

xtevent y, w(0 3) pol(z) impute(stag) plot

because there are no pre-event coefficients to test.

[jorpppp]

Summary: In this issue we addressed a bug when the user specified a left window of zero.

Thread continues in #194