Does anybody have a link to a precise definition of a "volume limited sample." This pertains especially to sky surveys that catalog galaxies. Due to limited precision, surveys tend to miss fainter galaxies as redshift increases. Thus, very loosely, I think, a volume limited sample filters out certain galaxies so that only galaxies of a finite brightness range are considered at all pertinent redshifts. However, I am looking for a precise definition, but can't seem to find one.