Illustration of a possible likelihood curve for a single Faraday depth measurement. The dotted line shows the likelihood arising from the n–π ambiguity of position angle measurements and the uncertainty in these measurements. The dashed curve shows an additional constraint on the magnitude of the source’s Faraday depth and the solid curve is the resulting combined likelihood curve, i.e., the product of the dotted and dashed curves. The plotted curves have been arbitrarily rescaled to show similar amplitudes.