Hello Everyone,
So after testing my var. with xtcips, several of my variables are not stationary at level,
I used xtcips since there is CD in data
My question is that; Can I use some variables as in the first order as following?
xtscc depvar indepvar indepvar2 d.indepvar3 d.indepvar4... indepvar15, fe lag(1)
xtscc because data heteroskedastic, autocorrelated, and CD.

If I cant use them in this regression, is there any other? (except ardl)
Because I think they are affecting depvar with their t-1.
For instance, 2019 indepvar3 may be affecting 2020 depvar.

If you can suggest any idea it would be great for me.
Thanks.