Distribution of H I column density for absorbers with and without metals (top) and with and without O VI absorption specifically (bottom). In the top panel no constraints are placed on the strength of the metal-line absorption or lack thereof. In the bottom panel, a cutoff of ﹩{N}_{{\rm{O}}{\rm{VI}}}={10}^{13.2}\,{\mathrm{cm}}^{-2}﹩ is used for the presence or absence of O VI absorption (i.e., only O VI absorbers with larger column densities are considered, and O VI must be detectable at the cutoff column density to at least ﹩3\sigma ﹩ significance for O VI nondetections).