In an ideal world we would have a one-to-one match when comparing predicted and experimental results, where each calculated pK a has a corresponding experimental value. When SAMPL6 was announced, it included specification for how the experimental pK a values would be measured. This included the limitation to perform experiments in a pH range of 2 -12. Following the organizer suggestions, we included predictions for all macroscopic pK a s our model predicted including those outside the specified experimental range. Thus, there are many molecules with fewer experimentally determined pK a s than we predicted. The organizers considered two matching algorithms and analyzed all challenge submissions with both methods. The first was a closest matching algorithm where each prediction is matched to an experimental value based on the absolute difference between them. If two predictions are paired to the same experimental value then the match with the larger absolute difference is thrown out leading to one less pair used in the analysis. To prevent the loss of data due to multiple pairings, the organizers redid the analysis using a Hungarian matching algorithm instead . In the Hungarian algorithm, the absolute difference is calculated for each pair of prediction to experiment. Then the combination of pairs which reduces the absolute error for that whole molecule is retained. One potential problem in this approach is that it does not account for the natural ordering of pK a values, meaning it is possible that the larger of two predictions could be paired with the smaller of two experimental pK a s. For example, if a molecule had two experimental pK a s 2.15 and 9.58 and a prediction reported values of 0.50 and 1.84, then the final pairs would be (9.58, 0.5) and (2.15, 1.84) as that would result in the smallest absolute error overall. In general, we believe the Hungarian approach is superior as it allows for all possible data to be included, though an ideal algorithm would restrict the order while matching. Fortunately, this reordering did not occur when our predictions were paired with experiment so we used the Hungarian matching to evaluate our performance. All analysis by organizers for all submissions can be found online (github.com/MobleyLab/SAMPL6).