Hello Teachers and professors
I have a question
I download a lot of data form datastream
after organizing to panel data
it has a lot of missing data
when I use reg, it can run
but I use "xtreg", it can't run
stata always reply "no observations"

what can I do?


clear
input int time float id double(a1 a2 a3)
17203 1 . . .
17231 1 . . .
17262 1 . . .
17292 1 . . .
17323 1 . . .
17353 1 . . .
17384 1 . . .
17415 1 . . .
17445 1 . . .
17476 1 . . .
17506 1 . . .
17537 1 . . .
17568 1 . . .
17597 1 . . .
17628 1 . . .
17658 1 . . .
17689 1 . . .
17719 1 . . .
17750 1 . . .
17781 1 . . .
17811 1 . . .
17842 1 . . .
17872 1 . . .
17903 1 . . .
17934 1 . . .
17962 1 . . .
17993 1 . . .
18023 1 . . .
18054 1 . . .
18084 1 . . .
18115 1 . . .
18146 1 . . .
18176 1 . . .
18207 1 . . .
18237 1 . . .
18268 1 . . .
18299 1 . . .
18327 1 . . .
18358 1 . . .
18388 1 . . .
18419 1 . . .
18449 1 . . .
18480 1 253.5 90.22 .
18511 1 281.9968 100.36 .
18541 1 312.8999 111.36 .
18572 1 414.5999 147.56 .
18602 1 375.5999 133.68 .
18633 1 355.5 126.52 .
18664 1 289.2 102.93 .
18692 1 239.7 85.31 .
18723 1 229.5 131.51 33.6
18753 1 210.6 120.68 30.8
18784 1 180.15 103.23 9.9
18814 1 158.7 90.94 8.7
18845 1 165.9 95.07 9.1
18876 1 173.4 99.37 9.5
18906 1 179.4 102.8 7.1
18937 1 209.7 120.17 8.2
18967 1 209.1 119.82 10.4
18998 1 209.829 171.67 10.4
19029 1 240.0001 196.35 11.9
19058 1 219 179.17 169.8
19089 1 229.2 204.04 177.7
19119 1 204.6 185.82 158.6
19150 1 135 122.61 104.7
19180 1 96.3 87.46 74.7
19211 1 87.6 79.56 .
19242 1 77.7 70.57 .
19272 1 81.3 73.84 .
19303 1 76.8 69.75 .
19333 1 86.4 78.47 .
19364 1 70.2 63.76 .
19395 1 45.6 41.42 .
19423 1 33.9 30.79 .
19454 1 28.491 25.88 .
19484 1 28.491 25.88 .
19515 1 28.491 25.88 .
19545 1 28.491 25.88 .
19576 1 28.491 25.88 .
19607 1 28.491 25.88 .
19637 1 28.491 42.55 .
19668 1 28.491 42.55 .
19698 1 28.491 42.55 .
19729 1 28.491 40.92 .
19760 1 28.491 40.92 .
19788 1 28.491 40.92 .
19819 1 28.491 40.92 .
19849 1 28.491 40.92 .
19880 1 7.5 8.88 .
19910 1 4.5 5.33 .
19941 1 3.9 4.62 .
19972 1 2.4 2.84 .
20002 1 2.1 2.49 .
20033 1 2.1 2.49 .
20063 1 1.2 1.42 .
20094 1 1.35 1.6 .
20125 1 .75 .89 .
20153 1 .9 1.07 .
20184 1 1.2 1.42 .
20214 1 .9 1.07 .
end
format %dCY/N/D time
xtset id time
xtreg a1 a2 a3, fe robust