Hi dear all i hope you all fine ...i am undergoing a problem in running analysis on the data ,the description of which is given below.my data in unbalanced panel data as it is evidence from the result of the stata commands like xtset and xt describe. i am confused wether to run SYSTEM GMM or not ...either it is feasible for this type or data or not...i am currently doing my MPhil research thesis i need your help...any reading material which can help me coming out of this problem will be highly appreciated.THANKING EVERYONE IN ANTICIPATION

xtset countrynum year
panel variable: countrynum (unbalanced)
time variable: year, 2001 to 2017
delta: 1 unit

. xtdescribe

countrynum: 1, 2, ..., 102 n = 102
year: 2001, 2002, ..., 2017 T = 17
Delta(year) = 1 unit
Span(year) = 17 periods
(countrynum*year uniquely identifies each observation)

Distribution of T_i: min 5% 25% 50% 75% 95% max
1 17 17 17 17 17 17

Freq. Percent Cum. | Pattern
---------------------------+-------------------
100 98.04 98.04 | 11111111111111111
1 0.98 99.02 | ................1
1 0.98 100.00 | 1111111111111111.
---------------------------+-------------------
102 100.00 | XXXXXXXXXXXXXXXXX