Relative parallax errors σ_ω∕ω for the bestmatches (reliability >0.8) sub-sample of confirmed PNe, along with the cumulative counts below various reliability thresholds for positive parallaxes (in black). The bins at either end represent the counts or matches with σ_ω ∕ω falling outside of the range (−0.5, 1.5). Within the sample, those parallaxes meeting more stringent criteria (reliability > 0.98, σ_ω < 0.2 mas, RUWE < 1.4, visibility_periods_used > 8) are indicated by the darker shaded area of the histogram. This subset is used for the Frew et al. (2016) distance comparisons.