DID regression COLLINEARITY problem

[Virginia Salaorni]

Hello to everyone,
I want to run a difference-in-differences regression with a control variable.

My variables are:
dependent (number of children, continuous)
time (survey wave, dichotomous)
treatment (dichotomous)
ttreated (interaction term between time and treatment)
control variable (employment, coded as 1=employed and 0=not employed)

I use the command:
reg dependent time treated ttreated i.employment, but what comes out is that time and ttreated are omitted because of collinearity.
I have other dichotomous covariates that does not give any problem.

Can someone help me?

Thank you!

[Carlo Lazzaro]

Virginia:
as per FAQ, without an excerpt/example of yuor dataset, that you can share via -dataex- it is difficult to reply positively.
As an aside, please see -fvvarlist- notation to create categorical variables and interactions.

[Virginia Salaorni]

Good evening,
thank you very much for your answer. Fortunately, I solved the problem!