  A statistical method is developed to infer the typical density profiles of
poor galaxy systems without resort to binning of data or assuming a given
center to each system. The method is applied to the accordant redshift quartets
in Hickson's compact groups (HCGs). The distribution of separations in these
groups is consistent with a unique generalized modified Hubble surface density
profile, with best-fit asymptotic slope beta = 1.4 and core radius R_c = 18
h^{-1} kpc, although a King profile (beta = 1) is also consistent with the data
(with R_c = 6 h^{-1} kpc). These distributions are more concentrated than what
has been previously determined for these groups. HCGs are unlikely to act as
strong gravitational lenses, but analogous systems 5 to 10 times more distant
should produce a non-negligible fraction of giant arcs.
