Comparison of z = 2.01 and z = 4.25 quasar luminosity functions between the SDSS-DR3 spectroscopic sample and our DR6 photometric quasar sample. The photometric quasar sample has been corrected for the magnitude dependent on the catalog's efficiency; however, it has not been corrected for the overall efficiency or completeness. Thus, the scaling of the DR6phot points is completely arbitrary. We have simply matched the curves near M _i = −29 to the DR3 sample. z ~ 2 quasars are given as squares, closed and open for the spectroscopic and photometric samples, respectively. There is excellent agreement between the z ~ 2 photometric and spectroscopic samples. z ~ 4 quasars are given as triangles, closed and open for the spectroscopic and photometric samples, respectively. For the z ~ 4.25 photometric sample, gray open triangles are objects with good ⩾ 0, while the black open triangles are more conservatively restricted to good ⩾ 1. Even for the more conservative sample, statistically significant flattening of the z ~ 4 QLF is evident in our data photometric data set.