  In this contribution we study the accuracy of various forms of electron
effective mass equation in reproducing spectral and spin-related features of
quantum dot systems. We compare the results of the standard 8 band k.p model to
those obtained from effective mass equations obtained by perturbative
elimination procedures in various approximations for a cylindrical quantum dot
or a system of two such dots. We calculate the splitting of electronic shells,
the electron g-factor and spin-orbit induced spin mixing and show that for a
cylindrical dot the g-factor is reproduced very exactly, while for the two
other quantities the effective mass equation is much less accurate.
