The Large Scale Structure ( LSS ) in the galaxy distribution is investigated using the Sloan Digital Sky Survey Early Data Release ( SDSS EDR ) .
Using the Minimal Spanning Tree technique we have extracted sets of filaments , of wall-like structures , of galaxy groups , and of rich clusters from this unique sample .
The physical properties of these structures were then measured and compared with the expectations from Zel ’ dovich ’ theory .

The measured characteristics of galaxy walls were found to be consistent with those for a spatially flat \Lambda CDM cosmological model with \Omega _ { m } \approx 0.3 and \Omega _ { \Lambda } \approx 0.7 , and for Gaussian initial perturbations with a Harrison – Zel ’ dovich power spectrum .
Furthermore , we found that the mass functions of groups and of unrelaxed structure elements generally fit well with the expectations from Zel ’ dovich ’ theory , although there was some discrepancy for lower mass groups which may be due to incompleteness in the selected sample of groups .
We also note that both groups and rich clusters tend to prefer the environments of walls , which tend to be of higher density , rather than the environments of filaments , which tend to be of lower density .

Finally , we note evidence of systematic differences in the properties of the LSS between the Northern Galactic Cap stripe and the Southern Galactic Cap stripe – in particular , in the physical properties of the walls , their spatial distribution , and the relative numbers of clusters embedded in walls .
Because the mean separation of walls is \approx 60 – 70 h ^ { -1 } Mpc , each stripe only intersects a few tens of walls .
Thus , small number statistics and cosmic variance are the likely drivers of these systematic differences .