This figure shows the distribution of values obtained for the variability parameters V_ν, a coefficient of variation, and η_ν, the significance of the variability (see text for full definitions) for each light curve detected. The upper panel shows the 55-min image results and the lower panel shows the 297-min time-scale results. In each case, the central panel plots the two values against each other for each source, with the top panel and right side panel displaying the histogram showing the distribution of the η_ν and V_ν values, respectively, for all sources. The dotted lines represent a 3σ threshold for each parameter. A very likely variable or transient source would appear in the top-right of the plot, exceeding a 3σ level in each parameter. At both time-scales, one source (3C 61.1) is found to have a significant value in η_ν. However, this is likely to arise from fluctuations caused by calibration issues.