We have noticed that Leaderboard scores were always higher than the private scores. We observed this difference for all our submissions as well as for all 100+ individual teams submissions from the challenge website. While models submitted by other teams could have inflated QWK scores for the Leaderboard set due selection of models with higher scores for this set, that was not a case for our analysis: we compared results without any model selection. Both the Leaderboard and private set scores were highly correlated (R 2 = 0.978) based on 100 submissions. The only exception was the submission of Dr. Rohde, which used plate-specific information. An inclusion of the plate-specific descriptors provided a model with a higher score for the private set also for our study. This result may indicate that there was some bias in selection of compounds for the Leaderboard and private sets, which could be due to the use of stratified data sampling for test sets or/and other reasons.