Hi everyone,
I am a college student and I have some questions about my econometrics report:

1, My professor told me that I have to use 300 obs and that is exactly what I did. However, when I ran the regression command, the obs fell down to only 18 obs. What should I do to fix this?
2, After I run xtgls to fix autocorrelation, what should I do next? Should I build a new function out of it or just describe the results?

I have email my professor but she hasn't replied to me yet.

I hope someone can help me with these