Eddington-Trumpler-Weaver bias. Evaluation of this bias for data from Muraveva et al. (2014), (top panel), and Pawlak et al. (2013), (bottom panel). The y-axis shows the difference between the value of the parallax from Gaia DR2 and the one derived from the assumed distance – 0.0208 ± 0.0005 mas for the LMC (top panel, Pietrzyński et al. 2013) and 0.0165 ± 0.0010 mas for the SMC (bottom panel, Hilditch et al. 2005)— divided by the quoted uncertainty (0.0005 mas, top panel, and 0.0010 mas, bottom panel). The x-axis shows the corresponding value of the relative error in parallax from Gaia DR2. Only sources with strictly positive values of the parallax are plotted; a sample of the full catalogues is shown as the full ranges in x and y are wider. The condition σ_π/π = 0.2 is plotted as a discontinuous line. Left panels: results without considering any global zero-point correction; right panels: include the correction (π + 0.029 mas) discussed in the text.