Log−Log plots of the NUV (left) and FUV (right) structure functions as a function of quasar luminosity (absolute i magnitude) for our sample of UV variable objects for rest frame time-lags of 1 d  <  10d and 100d  <  500d for QSOs with redshifts of 0.5  < z <  0.9 (open triangles) and z > 2.03 (filled circles) for the NUV data, and redshifts of 0.5 < z < 0.9 (open triangles) and 1.4 < z < 2.03 (asterisks). The data points have been connected by a continuous line for the 1 d  <  10d data, and by a dashed line for the 100d  <  500d data for ease of viewing.