Selection completeness ϵ_{sel   BOSS}(g,   z) for the quasars in the BOSS program. The significant drop at low redshift is due to the fact that many quasars with z < 1 appear as extended sources in coadded frames and were thus not considered in the initial source list. We also observe the expected efficiency drop at faint magnitudes. Bins left unfilled (white) are bereft of quasars.