The unbalanced panel consists of the population census. The unbalanced panel does not allow for generalizations of results, it is a conventional choice. I am using R with PLM package.
(1) Balancing generates a 70% loss of information, (2) Balancing loses time horizon of 2005-2013 to 2010-2013 (3) Balancing loses 70% of individuals, (4) inability to generalize results (5) Other _____________________.