[Joy Junial]

Freq. Percent Cum. | Pattern
---------------------------+-----------------------
33 97.06 97.06 | 111111111111111111111
1 2.94 100.00 | 111111111111.11111111
---------------------------+-----------------------
34 100.00 | XXXXXXXXXXXXXXXXXXXXX

Thanks, Andrew am learning big. Does it mean "1" under 33 is a suspect?

[Andrew Musau]

Indeed. You have 34 firms and 21 time periods. 33 firms have all observations present and 1 firm has an observation missing (Period 13). To see which:

bys firm_id (year_id): gen tag= _N<21
l firm_id year_id if tag, sepby(firm_id)