data is also seen in the ATCA data (Fig. \[fg:fluxes\]). Ball et al. (2001) stated that the MOST data after day 3000 were well fitted by a linear trend. However, we believe that there is significant evidence for an long-term increase in slope after day 3000 in both the MOST data set and the ATCA data sets, i.e., the rate of increase in flux density is increasing. Evidence for this is shown in Fig. \[fg:fluxvar\] which shows residual flux densities after fitting a second-order polynomial to the MOST and scaled ATCA flux densities from day 3000 and subtracting the linear component. These plots all show a systematic trend with the residual flux densities being, on average, negative at central times and positive at both early and late times. Fig. \[fg:fluxvar\] also shows the second-order term of the fit which in all cases is positive and of about 3-$\sigma$ significance. These data sets are essentially independent so there can be little doubt about the significance of the effect.

To further quantify this effect, straight lines were fitted to the ATCA data sets from day 3000, both for the unscaled data and for the data (except at 8.6 GHz) scaled by the 