The two different approaches for generating uncertainty-related heatmaps, UAA and AAU, target different kinds of atomic uncertainties. The first, uncertainty in atomic attributions (UAA), assesses how uncertain the model is in what attribution to give to each atom. Since the RF model is an ensemble model, we can in principle obtain a logP-heatmap from each tree in the model (in this case 200). We then use the standard deviation of the 200 predicted atomic attributions as a measure of how uncertain the model is of the atomic attribution. On the other hand, the atomic attribution to the uncertainty (AAU) aims at estimating how much each atom contributes to the overall uncertainty in the predicted logP. Thus, when we "remove an atom" we assign the difference in the uncertainty prediction to that atom as the atom's contribution to the uncertainty. Figure shows heatmaps of the UAA for the four molecules discussed so far, which generally emphasize the same parts of the molecules as the logP attributions, i.e. the atoms that contribute most to the logP value tend to have the highest uncertainties. However, the heatmaps for molecule 2 and 4 do indicate uncertainties for the cationic atoms that are higher than the corresponding logP contributions and similarly for the C atoms in the furan ring of 3. The AAU plots show a reverse trend where the highest uncertainties often are in regions that make relatively small logP contributions. The plots for molecules 3 and 4 show the highest uncertainties for the cationic atoms as well as the C atoms in the furan ring for 3. Interestingly, for molecule 2 the S atom of the sulfone group contributes significantly to the uncertainty in the logP prediction.