During the competition, teams were restricted to one submission per day, with a maximum of 102 submissions over the lifetime of the competition. Model selection and optimization requires a large number of analysis steps. Therefore, we approximated the submission QWK score using internal five-fold cross-validated RMSE. A similar strategy was used by us to predict the lowest effect level at the ToxCast challenge. This also contributed to less overfitting to the public submission set, and in theory generalizing to the unseen private submission set. QWK test sets were calculated after the end of the competition to provide more insight into the decision-making strategies.