Performance score stratified by confound

[raamana]

utils.score_stratified_by_confound()

Helper to summarize the performance score (accuracy, MSE, MAE etc) for each level or variant of confound. This is helpful to assess any bias towards a particular value when confounds are categorical (such as site or gender). So if the MSE (of target) for Females is much lower compared to Males, then it may indicate a potential bias of the model towards Females (due to imbalance in size?)