Quantifying Uncertainty in Random Forests via Confidence Intervals and Hypothesis Tests
This provides a statistical framework for uncertainty quantification in machine learning ensembles, addressing a key limitation for practitioners in fields requiring reliable predictions.
The paper tackles the lack of formal statistical inference in ensemble methods like random forests by proposing a U-statistic-based estimator that enables asymptotically normal predictions, allowing for confidence intervals and feature significance tests without extra computational cost, as validated through simulations and real data.
This work develops formal statistical inference procedures for machine learning ensemble methods. Ensemble methods based on bootstrapping, such as bagging and random forests, have improved the predictive accuracy of individual trees, but fail to provide a framework in which distributional results can be easily determined. Instead of aggregating full bootstrap samples, we consider predicting by averaging over trees built on subsamples of the training set and demonstrate that the resulting estimator takes the form of a U-statistic. As such, predictions for individual feature vectors are asymptotically normal, allowing for confidence intervals to accompany predictions. In practice, a subset of subsamples is used for computational speed; here our estimators take the form of incomplete U-statistics and equivalent results are derived. We further demonstrate that this setup provides a framework for testing the significance of features. Moreover, the internal estimation method we develop allows us to estimate the variance parameters and perform these inference procedures at no additional computational cost. Simulations and illustrations on a real dataset are provided.