Fig 2. The concept of using aggregate model prediction for model validation is shown.

The models predicted probabilities of postoperative opioid requirements in four buckets None/very low, Low, Medium and High. For model validation, the ability to predict within two adjacent buckets (None + Low, Low + Medium, Medium + High) was considered. The aggregate prediction bucket that had the highest combined prediction probability was considered as the model prediction. The predicted aggregate bucket was compared against the bucket corresponding to the actual opioid requirement for estimating the model accuracy.