Hey everyone! My name is Jesita. I am currently writing a paper regarding the impact of education decentralization on students' standardized test scores using IFLS panel data from 1993 to 2017 with 9,141 observations.
This is my result:

xtreg std_score1 i.MoEC i.Post i.MoEC##i.Post, robust cluster (commid) fe i(fcode)

Fixed-effects (within) regression Number of obs = 9336
Group variable: fcode Number of groups = 4800

R-sq: within = 0.0062 Obs per group: min = 1
between = 0.0114 avg = 1.9
overall = 0.0031 max = 5

F(3,313) = 6.55
corr(u_i, Xb) = -0.1643 Prob > F = 0.0003

(Std. Err. adjusted for 314 clusters in commid)
------------------------------------------------------------------------------
| Robust
std_score1 | Coef. Std. Err. t P>|t| [95% Conf. Interval]
-------------+----------------------------------------------------------------
1.MoEC | .0119933 .0575029 0.21 0.835 -.1011477 .1251343
1.Post | .2059144 .0610805 3.37 0.001 .0857341 .3260946
|
MoEC#Post |
1 1 | -.2950334 .0673567 -4.38 0.000 -.4275625 -.1625043
|
_cons | -.0060922 .0395492 -0.15 0.878 -.083908 .0717237
-------------+----------------------------------------------------------------
sigma_u | .94483298
sigma_e | .82235053
rho | .56897805 (fraction of variance due to u_i)
------------------------------------------------------------------------------

The conclusion is that: "decentralization negatively affect students' test scores"
I ran the balanced panel and full sample analysis, with or without controls, and the results are consistent.
My biggest question: How do I know that the result is robust and correct? I know I cannot use "diff" command because my data is panel.
Please help me. Thank you so much.