Variability-absolute magnitude relations (top) and variability-redshift relations (middle) for the five SDSS bands. The bottom line compares the measured z gradient of variability (solid) with the z gradient expected from the dependence of V on M_i(z) (dashed). (Note that the M_i are K-corrected in the rest-frame, yet the V_k refer to photometric bands defined in the observer frame.)