I am using XGBoost to build mortgage prepayment models trained at the loan level. Early stopping is based on AUC scores. The first 18 training rounds are 0.50 and 0.50 test and train, respectively. To get around this I set early stopping at 20. This solves my immediate problem of early stopping. The model trains well achieving an auc of 0.70 - which in this case is very good. To finish the code I think I need to get past the 0.50 and 0.5 auc in earlier rounds. Does anyone have a suggestion as to how achieve something like this?