How Stata estimates random effects for an unbalanced panel data

[Ruben Ba]

I have estimated a random effects model with an unbalanced panel. I would like to know if Stata gives each individual the same weight when estimating the coefficients or whether each individual is weighted differently depending on the time units(years) available.
I have tried to find the answer in the usual documentation of xtreg and in other statalist posts, unsuccessfully so far. Any comment/source hugely appreciated!

[Nick Cox]

Cross-posted at http://stats.stackexchange.com/quest...balanced-panel

(You were advised there to post here, so that's fine, but as the FAQ Advice does state, you are asked to tell us about cross-posting too.)