[Gretl-users] Panel Regression Model: Fixed Effect, Random Effects, or OLS Regression?

Dear Experts, 1. If there is heterogeneity in the panel model/data, is it true that the appropriate model is either the Fixed Effect or Random Effects model? 2. I want to choose the appropriate panel regression model when there are autocorrelations, heterogeneity, multicollinearity, and non-normality. Any guiding non-highly mathematical materials that you can suggest? Thank you.