SDSS colors vs. redshift for quasars in the DR9Q catalog. The thin solid red line is the median color in bins of redshift. The thick color lines are models from simulations used to determine the BOSS quasar completeness (McGreer et al., in prep.; see also Ross et al., in prep.) for three different quasar luminosities: M_i [z = 2] = −22.49 (cyan), M_i [z = 2] = −24.99 (green) and M_i [z = 2] = −27.49 (orange); and empirical tracks for the DR7 quasars (blue Bovy et al. 2011). These simulations include the Baldwin effect (Baldwin 1977). Therefore the colors depend on the quasar luminosity. The model is systematically bluer than the data at low redshift because BOSS systematically excludes UV-excess sources.