Comparison of Bayes factors between warm absorber models. The Bayes factor for the warm absorption model is shown on the horizontal axis, while the Bayes factor for the neutral partial covering model is shown on the vertical axis. The dashed grey line shows the one-to-one relation, with sources lying below the line being better fit with the PL+WA model, and sources above the line being better fit with the PL+PCF model. Sources which do not show evidence for any complex absorption are shown in grey. The values of K_wa = 1.126 and K_pcf = 1.555 correspond to purities of 97.5%.