  Using a sample of nine massive compact galaxies at z ~ 2.3 with rest-frame
optical spectroscopy and comprehensive U through 8um photometry we investigate
how assumptions in SED modeling change the stellar mass estimates of these
galaxies, and how this affects our interpretation of their size evolution. The
SEDs are fit to Tau-models with a range of metallicities, dust laws, as well as
different stellar population synthesis codes. These models indicate masses
equal to, or slightly smaller than our default masses. The maximum difference
is 0.16 dex for each parameter considered, and only 0.18 dex for the most
extreme combination of parameters. Two-component populations with a maximally
old stellar population superposed with a young component provide reasonable
fits to these SEDs using the models of Bruzual & Charlot (2003); however, using
models with updated treatment of TP-AGB stars the fits are poorer. The
two-component models predict masses that are 0.08 to 0.22 dex larger than the
Tau-models. We also test the effect of a bottom-light IMF and find that it
would reduce the masses of these galaxies by 0.3 dex. Considering the range of
allowable masses from the Tau-models, two-component fits, and IMF, we conclude
that on average these galaxies lie below the mass-size relation of galaxies in
the local universe by a factor of 3-9, depending on the SED models used.
