Dear all,

I am currently working on a thesis project on railway competition in the EU. I am using a fixed effects in a panel data setting and the following command: xtreg Y Var1..., fe robust

I suspect that there are differences between Western and Eastern European countries. Thus, I would like to control for this by establishing a Western and Eastern group and afterwards estimate the effect of being in one group on my dependent variable. I have tried with a dummy variable but it was omitted due to collinearity.

Could anyone help me with how to proceed?

Thank you very much!
Kind regards,
Kasper Trier