Dear Stata users,

I don't have a lot of experience using the software and I'm currently working on my master's thesis, so I really need your help.

I have a panel data (65 countries, 12 years per country) and it is strongly balanced. Since I have to run several robustness tests (regressions) to finally come up with strong final results, I know the commands to run panel data regression ( xtset ... xtreg, fe , re, be...) However, my main problem is that I'm not sure if I'm a running the right Pooled OLS regressions with robust standard errors.

Is this code correct to use Pooled OLS with robust standard errors????? Should I use robust or vce (cluster country_code)... I'm not sure if I should cluster by country, to be honest it doesn't make sense to me, I believe clustering is useful only if you have firms of the same industry or households information within the countries... which is not my case, I'm working with country data only.

reg dependvar regressor1 regressor2 .... regressor_n, robust

or Should I use:

reg dependvar regressor1 regressor2 .... regressor_n, vce (cluster country_code)

Another question, some of the papers similar to my thesis run a fixed effect and random effect models using one lag of the dependent variable... how can I include one lag of the dependent variable in the fixed and random effect models?

xtreg dependvar regressor1 regressor2 .... regressor_n l.dependedvar, fe robust .... is this ok?

Thanks for any help you can give me.

Regards,
Ivan