version 13.1 use https://www3.nd.edu/~rwilliam/statafiles/teenpovxt, clear xtlogit pov i.mother i.spouse i.school hours i.year, fe nolog xtlogit, or xtlogit pov i.mother i.spouse i.school hours i.year age i.black, fe nolog use https://www3.nd.edu/~rwilliam/statafiles/teenpovxt, clear xtset, clear clogit pov i.mother i.spouse i.school hours i.year, group(id) nolog