Discrete Fourier analysis on the quasar number count , as a function of redshift , z , calculated from the Sloan Digital Sky Survey DR6 release appears to indicate that quasars have preferred periodic redshifts with redshift intervals of 0.258 , 0.312 , 0.44 , 0.63 , and 1.1 .
However the same periods are found in the mean of the zConf parameter used to flag the reliability of the spectroscopic measurements .
It follows that these redshift periods must result from some selection effect , as yet undetermined .
It does not signal any intrinsic ( quantized ) redshifts in the quasars .