  It has been demonstrated that planets belonging to the same close-in, compact
multiple-planet system tend to exhibit a striking degree of uniformity in their
sizes. A similar trend has also been found to hold for the masses of such
planets, but considerations of such intra-system mass uniformity have generally
been limited to statistical samples wherein a majority of systems have
constituent planetary mass measurements obtained via analysis of transit timing
variations (TTVs). Since systems with strong TTV signals typically lie in or
near mean motion resonance, it remains to be seen whether intra-system mass
uniformity is still readily emergent for non-resonant systems with non-TTV mass
provenance. We thus present in this work a mass uniformity analysis of 17
non-TTV systems with masses measured via radial velocity (RV) measurements.
Using the Gini index, a common statistic for economic inequality, as our
primary metric for uniformity, we find that our sample of 17 non-TTV systems
displays intra-system mass uniformity at a level of $\sim 2.5 \sigma$
confidence. We provide additional discussion of possible statistical and
astrophysical underpinnings for this result. We also demonstrate the existence
of a correlation ($r = 0.25$) between characteristic solid surface density
($\Sigma_0$) of the minimum mass extrasolar nebula (MMEN) and system mass Gini
index, suggesting that more massive disks may generally form systems with more
unequal planetary masses.
