Bayes factor K calculated between the standard and the porous models as Z_standard/Z_porous, for the nonscattering model (upper panel) and scattering model (lower panel). The different markers correspond to the different size distribution coefficients q. The points are color-coded according to their values: K > 1 (larger evidence for the standard composition) are drawn in cyan and K < 1 (larger evidence for porous composition) in magenta. Empty markers correspond to 1 < K < 3 or 1/3 < K < 1, full markers to K > 3 or K < 1/3. The horizontal dashed line is drawn at K = 10, so that all points above this line correspond to a strong evidence in favor of standard grains. The points larger than 100 are drawn at the location of 100, since for K ≥ 100 the interpretation in terms of evidence strength does not change (see Sect. 3.4).