  The virial, projected and spherical Jeans equation galaxy mass estimators are
compared. High-resolution models of elliptical galaxies from N-body simulations
are used to compare predicted mass profiles. Averages over eight models and
directions in the three intrinsic projections show that all the mass estimators
are comparably poor for r<4 kpc but that, with the exception of the projected
mass estimator, errors are within approximately 10 - 20% out to r=40 kpc.
Because kinematic data for elliptical galaxies are now available out to several
effective radii, mass estimation techniques which are simple to apply can
provide mass profiles and mass-to-light ratios at large radii.
