Number of sources identified in each of the four variability categories, for the two variability identifiers SCATT_LO and AMPL_SIG. We added the numbers of sources in each of the 16 categories from the three separate analyses of the three individual eRASSs. This means that many sources will appear up to three times in this figure, possibly in different regions. All four categories exclude sources at a higher variability significance. For example, sources that are shown to lie in the bin >1σ do not include the sources observed with a variability significance of >2σ.