In addition to the coefficient of determination (R2), several other metrics can be employed to evaluate and predict the performance of policy filtration strategies:
Mean Squared Error (MSE): MSE can be used to quantify the average squared difference between the predicted rewards from the reward model and the actual scores. A lower MSE indicates a more reliable reward model, which can correlate with better policy performance.
Spearman's Rank Correlation Coefficient: This non-parametric measure assesses how well the relationship between two variables can be described by a monotonic function. It can be particularly useful in evaluating the rank order of responses based on their rewards and actual performance, providing insights into the effectiveness of the filtration strategy.
Precision-Recall Metrics: Metrics such as precision and recall can be applied to evaluate the quality of the responses selected by the filtration strategy. High precision indicates that most of the selected responses are relevant, while high recall indicates that most relevant responses are captured.
F1 Score: The F1 score, which combines precision and recall into a single metric, can provide a balanced view of the filtration strategy's effectiveness, especially in scenarios where there is an uneven class distribution of rewards.
Area Under the Receiver Operating Characteristic Curve (AUC-ROC): This metric can be used to evaluate the trade-off between true positive rates and false positive rates across different thresholds, helping to assess the overall performance of the reward model in distinguishing between high-quality and low-quality responses.