(a) Redshift versus L_4.6 luminosity. Red circles and blue dots denote the selected dust-obscured quasars and SDSS quasars, respectively. Among the blue dots, 300 blue dots with black edges represent the L_4.6–z matched SDSS quasars, which were used as unobscured quasars. (b) Redshift distributions of the two kinds of quasars. Red and blue histograms represent the dust-obscured quasars and the unobscured quasars, respectively.