Hello,

I have a panel data with 115 countries and 20 years. I did unit root test in all my independent variables and the dependent. From my results, I have the presence of unit root in some of the independent and the dependent. According to the literature that I'm following, I need to add a deterministic trend to my model.

This is my original regression:

Code:
xi:reg reconsumption lngdppppcte2011lag1 manufacturinglag1 lnoilpricelag1 energyimportslag1 leftlag4 i.country, robust
How do I add a deterministic trend to panel data?

I thought that adding
Code:
i.year
was enough but I was told that is not the correct way. Now I don't know how to proceed.


Thanks in advance!