Left: average reported uncertainties in polarization, $\overline{{\sigma }_P}$, versus ${\chi }_{\nu }^2$ for targets that survive the cuts described in Sect. 3.1, but without any restriction for the error bars. The black line is a linear fit for all the data in log-log space. The dashed blue line is similar, but excluding the points in the top left of the plot. Right: similar to left, but with the restriction for the error bars of σ_P ≥ 0.1%.