Extragalactic contribution to each source’s observed Faraday depth versus Galactic latitude for the simulated scenario discussed in Sect. 3.3. Upper panel: approximate posterior mean estimate as calculated by our algorithm, lower panel: random sample drawn from the posterior PDF. The density of data points of the SIP category, i.e., with noise variance correction factors, is plotted in grayscale, data points of the VIP category, i.e., without noise variance correction factors, are plotted as green +−signs.