Bivariate distribution of the ratio between the standard deviation of B_⊥ and its median value, μ, and the polarisation fraction, p, computed at 130 MHz for each LOS for the weak and strong field cases (upper and lower panel, respectively), at a resolution of 6.7′. The POSs are identified by the three different colours displayed in the legend. Isodensity contours are plotted at 5, 30, 50, and 75% levels. The histograms above and to the right of the main plots show the marginal distribution of the two quantities. The median values are marked by horizontal and vertical lines and are listed in Table 3.