Hello

I'm trying to make a pooled OLS regression for the years t=2 (1992 and 1999) and for the regions t = 2 (East and West)

These are survey data and I have for the year 1992, 749 observations and for the year 1999, 880 observations.

My codes look like this:

Code:
sort region year
egen panel_id = group(region)
sort panel_id year
xtset panel_id year
as soon as I type "xtset panel_id year", I get the answer "repeated time values within panel." I tried to find something about it, but I don't understand exactly where the problem lies.