Distributions of the variability amplitude proxy of sources in the Gaia DR2 archive. The black histogram represents all sources brighter than G = 19 mag with mean G flux over error ratios I_G/ε(I_G) < 600. The filled green histogram represents the sources published in the specific DR2 catalogue of LPVs. The vertical red dashed line locates the A_proxy, G = 0.06 limit used to select large-amplitude variable candidates in this study.