  Several statistics are applied to groups and galaxies in groups in the Two
degree Field Galaxy Redshift Survey. Firstly we estimate the luminosity
functions for different subsets of galaxies in groups. The results are well
fitted by a Schechter function with parameters $M^{\ast}-5\log(h)=-19.90 \pm
0.03$ and $\alpha=-1.13\pm0.02$ for all galaxies in groups, which is quite
consistent with the results by Norberg et al. for field galaxies. When
considering the four different spectral types defined by Madgwick et al. we
find that the characteristic magnitude is typically brighter than in the field.
We also observe a steeper value, $\alpha=-0.76\pm 0.03$, of the faint end slope
for low star-forming galaxies when compared with the corresponding field value.
This steepening is more conspicuous, $\alpha=-1.10\pm 0.06$, for those galaxies
in more massive groups (${\mathcal M} \gsim 10^{14} h^{-1} M_{\odot}$) than the
obtained in the lower mass subset, $\alpha=-0.71\pm 0.04$ (${\mathcal
M}<10^{14} h^{-1} M_{\odot}$). Secondly, we compute group total luminosities
using Moore, Frenk & White prescriptions. We define a flux-limited group sample
using a new statistical tool developed by Rauzy. The resulting group sample is
used to determine the group luminosity function finding a good agreement with
previous determinations and semianalytical models. Finally, the group mass
function for the flux-limited sample is derived. An excellent agreement is
obtained when comparing our determination with analytical predictions over two
orders of magnitude in mass.
