I want regress difference model in panel data.
using two year data, for example, I want to estimate the effect of independent variable with trend.
but the problem is that when I use the gen time=_n, the time order is mixed up every time, so the result became different whenever I analyze.
The other problem is that if I made the time variable , for example 1, 2 for every id, because of colinearity, it came out zero
How can I handle that?