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 \pm 0.02 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 } } \mathrel { \hbox { \hbox to 0.0 pt { \hbox { \lower 4.0 pt \hbox { $ \sim$ } } } % \hbox { $ > $ } } } 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 .