how to choose between Fixed effects model and Pooled OLS model ?

[paty solevan]

hello everyone,
i'm currenlty doing a research for my masters' thesis, and i'm doing a panel study of 28 OECD countries over the span of 28 years.
I have run a pooled OLS model,
and i have also run Fixed effects model and random effects model, and after running the Hausman test, i rejected the null hypothesis meaning that the fixed effects model is more appropriate.
my question now is how i go from here? how do i choose between Pooled OLS model and Fixed effects model, is there a test that i can run ?
thank you in advance and best regards,



this is my Pooled OLS model.

Fixed Effects model:

Random Effects model:

[Andrew Musau]

https://www.statalist.org/forums/for...s-fixed-effect

[paty solevan]

Thank you, Andrew Musau for you reply.
i have seen the answer in the link you posted, however unlike on that post when i run the testparm on stata, i don't get the same same test statistic as obtained under xtreg

what i get is this:

under Fixed Effects:

F test that all u_i=0: F(23, 186) = 89.28
Prob > F = 0.0000



under Pooled OLS:

F( 12, 197) = 1.96
Prob > F = 0.0301

and i'm not sure how to interpret this, or what to conclude from it.

thank you in advance.

[Carlo Lazzaro]

Paty:
you're comparing two different pieces of information.
The first F-test is the one appearing in the top-right corner of the -regress- and -xtreg,fe. output: it tests whether your predictors are jointly different from zero.
The second F-test appears as a footnote of the -xtreg,fe- table and tests whether there'sevidence of panel-wise effect (as it is in your case).