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. The data are plotted in bins of 2 mag width and are shown for four rest frame time-lags (t) of 1d  < t ≤  10d (crosses), 10d  < t ≤  100d (asterisks), 100d  < t ≤  500d (open circles) and  > 500d (filled circles) for both the NUV and FUV observations. Best-fit lines to the data points are also shown, revealing that NUV and FUV variability amplitudes are greater at longer time-lags than for shorter time-lags for all values of QSO luminosity