[NMusers] unbalanced design

[Mark Sale - Next Level Solutions]

Does anyone have a reference to a publication assessing whether mixed effect modeling (NONMEM in particular) is robust for unbalances studies?  I see if in a number of courses (including the original beginners course for NONMEM), but can't find a publication. thanks Mark Sale MD Next Level Solutions, LLC www.NextLevelSolns.com 919-846-9185