H₂-to-H i ratio, R_H2, of each map point as a function of the total surface density, Σ_{H i} + Σ_H2, compared with the predictions of the Krumholz et al. (2009) model (red curves, taken from their Eq. (39)). The green triangles indicate the mean R_H2 values measured within the rings used in Fig. 7. The R_H2 ratio values measured throughout the W43 molecular complex and its surroundings are in striking disagreement with the fiducial model of Krumholz et al. (2009).