Top: mean values of parallaxes plotted against σ_{5d,  max}. Middle: standard deviations of the normalised centred parallaxes plotted against σ_{5d,  max}. Bottom: mean values of normalised proper motion difference X_pm plotted against σ_{5d,  max}. Dashed lines represent the mean values of the full sample. Horizontal error bar represents the standard deviation of σ_{5d,  max} in subsets. Sources are sorted by σ_{5d,  max} and divided into subsets. Each dot above is calculated in bins of 10 000 sources, except for the last one containing 6869 quasars.