Efficient distributional regression trees learning algorithms for calibrated non-parametric probabilistic forecasts
Pith reviewed 2026-05-23 03:14 UTC · model grok-4.3
The pith
New algorithms learn probabilistic regression trees efficiently for WIS and CRPS losses by integrating min-max heaps, weight-balanced binary trees, and Fenwick trees.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The paper presents algorithms that learn distributional regression trees by optimizing splits for WIS or CRPS, with efficiency from appropriate data structures, demonstrating competitive performance in numerical experiments and suitability for conformal prediction.
What carries the argument
Integration of min-max heaps, weight-balanced binary trees, and Fenwick trees into the tree learning process to compute optimal splits under WIS or CRPS losses.
If this is right
- The learned trees produce non-parametric probabilistic forecasts with good calibration and coverage properties.
- The trees maintain interpretability and explainability advantages of standard decision trees.
- The methods achieve competitive performance with alternative approaches on benchmark tasks.
- The trees are well-suited for conformal prediction to achieve group-conditional coverage guarantees.
Where Pith is reading between the lines
- These algorithms could extend to other proper scoring rules beyond WIS and CRPS.
- The data structures may enable scaling to much larger datasets than naive implementations allow.
- The approach could combine with ensemble methods to further improve forecast reliability.
Load-bearing premise
The data structures integrate into the tree learning process without introducing hidden computational costs or approximation errors that compromise calibration or coverage.
What would settle it
A dataset where training the new algorithms takes significantly longer than expected or results in poorer CRPS scores and coverage compared to baseline methods.
Figures
read the original abstract
The perspective of developing trustworthy AI for critical applications in science and engineering requires machine learning techniques that are capable of estimating their own uncertainty. In the context of regression, instead of estimating a conditional mean, this can be achieved by producing a predictive interval for the output, or to even learn a model of the conditional probability $p(y|x)$ of an output $y$ given input features $x$. While this can be done under parametric assumptions with, e.g. generalized linear model, these are typically too strong, and non-parametric models offer flexible alternatives. In particular, for scalar outputs, learning directly a model of the conditional cumulative distribution function of $y$ given $x$ can lead to more precise probabilistic estimates, and the use of proper scoring rules such as the weighted interval score (WIS) and the continuous ranked probability score (CRPS) lead to better coverage and calibration properties. This paper introduces novel algorithms for learning probabilistic regression trees for the WIS or CRPS loss functions. These algorithms are made computationally efficient thanks to an appropriate use of known data structures - namely min-max heaps, weight-balanced binary trees and Fenwick trees. Through numerical experiments, we demonstrate that the performance of our methods is competitive with alternative approaches. Additionally, our methods benefit from the inherent interpretability and explainability of trees. As a by-product, we show how our trees can be used in the context of conformal prediction and explain why they are particularly well-suited for achieving group-conditional coverage guarantees.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript introduces novel algorithms for learning probabilistic regression trees optimized exactly for the weighted interval score (WIS) or continuous ranked probability score (CRPS). Computational efficiency during split evaluation is obtained by integrating min-max heaps, weight-balanced binary trees, and Fenwick trees for dynamic order statistics and prefix aggregates. Numerical experiments are reported to show competitive performance against alternative approaches; the tree structure is additionally shown to support conformal prediction with group-conditional coverage guarantees.
Significance. If the exactness and complexity claims hold, the work supplies an interpretable non-parametric method for distributional regression that directly optimizes proper scoring rules, thereby improving calibration and coverage relative to mean-focused trees. The explicit use of standard data structures for order-statistic queries is a positive feature that aligns with the requirements of split-score computation.
minor comments (3)
- [§3] §3 (algorithm description): the integration of the three data structures is described at a high level; an explicit walk-through of one split-score update (including the sequence of heap/BST/Fenwick operations) would make the claimed O(log n) per candidate split verifiable.
- [Table 2] Table 2 (or equivalent results table): the reported runtimes should include a column for the naïve O(n log n) baseline per split so that the practical speed-up factor is directly visible.
- [§5.2] §5.2 (conformal prediction): the argument for group-conditional coverage relies on the tree partitioning; a short proof sketch or reference to the relevant property of the learned partitions would strengthen the claim.
Simulated Author's Rebuttal
We thank the referee for the positive summary, significance assessment, and recommendation of minor revision. No major comments were provided in the report.
Circularity Check
No significant circularity
full rationale
The paper's central contribution consists of new algorithmic constructions for exact optimization of WIS/CRPS losses inside regression trees, achieved by integrating standard external data structures (min-max heaps, weight-balanced BSTs, Fenwick trees) for dynamic order statistics and prefix aggregates. These structures are invoked as known primitives whose properties are independent of the present work; the efficiency claims and the conformal-prediction by-product follow directly from the tree structure and the loss definitions without any reduction to fitted parameters, self-definitional loops, or load-bearing self-citations. The derivation chain therefore remains self-contained against external benchmarks.
Axiom & Free-Parameter Ledger
axioms (1)
- standard math Min-max heaps, weight-balanced binary trees, and Fenwick trees support the required update and query operations in logarithmic time as established in computer science literature.
Reference graph
Works this paper leans on
-
[1]
Variational inference for nonparametric B ayesian quantile regression
Sachinthaka Abeywardana and Fabio Ramos. Variational inference for nonparametric B ayesian quantile regression. Proceedings of the AAAI Conference on Artificial Intelligence , 29(1), Feb. 2015
work page 2015
-
[2]
L. Breiman, J. Friedman, C.J. Stone, and R.A. Olshen. Classification and Regression Trees . Taylor & Francis, 1984
work page 1984
-
[3]
Jonas R. Brehmer and Tilmann Gneiting. Scoring interval forecasts: Equal-tailed, shortest, and modal interval. Bernoulli , 27(3), May 2021
work page 2021
-
[4]
Towards scalable quantile regression trees
Harish S Bhat, Nitesh Kumar, and Garnet J Vaz. Towards scalable quantile regression trees. In 2015 IEEE International Conference on Big Data (Big Data) , pages 53--60. IEEE, 2015
work page 2015
-
[5]
Classification and regression trees
Leo Breiman. Classification and regression trees . Routledge, 2017
work page 2017
-
[6]
Ray, Tilmann Gneiting, and Nicholas G
Johannes Bracher, Evan L. Ray, Tilmann Gneiting, and Nicholas G. Reich. Evaluating epidemic forecasts in an interval format. PLOS Computational Biology , 17(2):1--15, 02 2021
work page 2021
-
[7]
Fenchel- Y oung losses with skewed entropies for class-posterior probability estimation
Han Bao and Masashi Sugiyama. Fenchel- Y oung losses with skewed entropies for class-posterior probability estimation. In International Conference on Artificial Intelligence and Statistics , pages 1648--1656. PMLR, 2021
work page 2021
-
[8]
Alex J. Cannon. Quantile regression neural networks: Implementation in r and application to precipitation downscaling. Computers & Geosciences , 37(9):1277--1284, 2011
work page 2011
-
[9]
ACCRUE: A ccurate and reliable uncertainty estimate in deterministic models
Enrico Camporeale and Algo Car \`e . ACCRUE: A ccurate and reliable uncertainty estimate in deterministic models. International Journal for Uncertainty Quantification , 11(4), 2021
work page 2021
-
[10]
Distributional conformal prediction
Victor Chernozhukov, Kaspar W \"u thrich, and Yinchu Zhu. Distributional conformal prediction. Proceedings of the National Academy of Sciences , 118(48):e2107794118, 2021
work page 2021
-
[11]
M. H. DeGroot. Uncertainty, Information, and Sequential Experiments . The Annals of Mathematical Statistics , 33(2):404 -- 419, 1962
work page 1962
-
[12]
David B Dunson, Natesh Pillai, and Ju-Hyun Park. Bayesian density regression. Journal of the Royal Statistical Society Series B: Statistical Methodology , 69(2):163--183, 2007
work page 2007
-
[13]
Robert F Engle and Simone Manganelli. Caviar. Journal of Business & Economic Statistics , 22(4):367--381, 2004
work page 2004
-
[14]
Peter D. Gr \"u nwald and A. Philip Dawid. Game theory, maximum entropy, minimum discrepancy and robust B ayesian decision theory . The Annals of Statistics , 32(4):1367 -- 1433, 2004
work page 2004
-
[15]
Nested conformal prediction and quantile out-of-bag ensemble methods
Chirag Gupta, Arun K Kuchibhotla, and Aaditya Ramdas. Nested conformal prediction and quantile out-of-bag ensemble methods. Pattern Recognition , 127:108496, 2022
work page 2022
-
[16]
Fitting finite mixtures of generalized linear regressions in R
Bettina Gr \"u n and Friedrich Leisch. Fitting finite mixtures of generalized linear regressions in R . Computational Statistics & Data Analysis , 51(11):5247--5252, 2007
work page 2007
-
[17]
Strictly proper scoring rules, prediction, and estimation
Tilmann Gneiting and Adrian E Raftery. Strictly proper scoring rules, prediction, and estimation. Journal of the American statistical Association , 102(477):359--378, 2007
work page 2007
-
[18]
S. Halim and F. Halim. Competitive P rogramming 3: T he New Lower Bound of Programming Contests . Number vol. 3. Lulu.com, 2013
work page 2013
-
[19]
Denoising diffusion probabilistic models
Jonathan Ho, Ajay Jain, and Pieter Abbeel. Denoising diffusion probabilistic models. Advances in neural information processing systems , 33:6840--6851, 2020
work page 2020
-
[20]
James T. Hamilton and W Viscusi. Are risk regulators rational? evidence from hazardous waste cleanup decisions. American Economic Review , 89(4):1010--1027, 1999
work page 1999
-
[21]
Evaluating probabilistic forecasts with scoringRules
Alexander Jordan, Fabian Kr \"u ger, and Sebastian Lerch. Evaluating probabilistic forecasts with scoringRules . arXiv preprint arXiv:1709.04743 , 2017
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[22]
A multiple quantile regression approach to the wind, solar, and price tracks of GEFCom2014
Romain Juban, Henrik Ohlsson, Mehdi Maasoumy, Louis Poirier, and J Zico Kolter. A multiple quantile regression approach to the wind, solar, and price tracks of GEFCom2014 . International Journal of Forecasting , 32(3):1094--1102, 2016
work page 2016
-
[23]
Roger Koenker and Gilbert Bassett Jr. Regression quantiles. Econometrica: journal of the Econometric Society , pages 33--50, 1978
work page 1978
-
[24]
Normalizing flows: A n introduction and review of current methods
Ivan Kobyzev, Simon JD Prince, and Marcus A Brubaker. Normalizing flows: A n introduction and review of current methods. IEEE transactions on pattern analysis and machine intelligence , 43(11):3964--3979, 2020
work page 2020
-
[25]
Quantiles based personalized treatment selection for multivariate outcomes and multiple treatments
Karunarathna B Kulasekera and Chathura Siriwardhana. Quantiles based personalized treatment selection for multivariate outcomes and multiple treatments. Statistics in medicine , 41(15):2695--2710, 2022
work page 2022
-
[26]
Rage against the mean – a review of distributional regression approaches
Thomas Kneib, Alexander Silbersdorff, and Benjamin Säfken. Rage against the mean – a review of distributional regression approaches. Econometrics and Statistics , 26:99--123, 2023
work page 2023
-
[27]
Stepwise multiple quantile regression estimation using non-crossing constraints
Yufeng Liu and Yichao Wu. Stepwise multiple quantile regression estimation using non-crossing constraints. Statistics and its Interface , 2(3):299--310, 2009
work page 2009
-
[28]
Nicolai Meinshausen and Greg Ridgeway. Quantile regression forests. Journal of machine learning research , 7(6), 2006
work page 2006
-
[29]
Handbook of data structures and applications
Dinesh P Mehta and Sartaj Sahni. Handbook of data structures and applications . Chapman and Hall/CRC, 2004
work page 2004
-
[30]
Generalized maximum entropy for supervised classification
Santiago Mazuelas, Yuan Shen, and Aritz Pérez. Generalized maximum entropy for supervised classification. IEEE Transactions on Information Theory , 68(4):2530--2550, 2022
work page 2022
-
[31]
J. Nievergelt and E. M. Reingold. Binary search trees of bounded balance. SIAM Journal on Computing , 2(1):33--43, 1973
work page 1973
-
[32]
High-resolution image synthesis with latent diffusion models
Robin Rombach, Andreas Blattmann, Dominik Lorenz, Patrick Esser, and Bj \"o rn Ommer. High-resolution image synthesis with latent diffusion models. In Proceedings of the IEEE/CVF conference on computer vision and pattern recognition , pages 10684--10695, 2022
work page 2022
-
[33]
Handbook of quantile regression
Quantile Regression. Handbook of quantile regression . CRC Press: Boca Raton, FL, USA, 2017
work page 2017
-
[34]
Conformalized quantile regression
Yaniv Romano, Evan Patterson, and Emmanuel Candes. Conformalized quantile regression. Advances in neural information processing systems , 32, 2019
work page 2019
-
[35]
R. A. Rigby and D. M. Stasinopoulos. Generalized Additive Models for Location, Scale and Shape . Journal of the Royal Statistical Society Series C: Applied Statistics , 54(3):507--554, 04 2005
work page 2005
-
[36]
A comparison of some conformal quantile regression methods
Matteo Sesia and Emmanuel J Cand \`e s. A comparison of some conformal quantile regression methods. Stat , 9(1):e261, 2020
work page 2020
-
[37]
Engression: Extrapolation through the lens of distributional regression, 2024
Xinwei Shen and Nicolai Meinshausen. Engression: Extrapolation through the lens of distributional regression, 2024
work page 2024
-
[38]
Bayesian nonparametric quantile regression using splines
Paul Thompson, Yuzhi Cai, Rana Moyeed, Dominic Reeve, and Julian Stander. Bayesian nonparametric quantile regression using splines. Computational Statistics & Data Analysis , 54(4):1138--1150, 2010
work page 2010
-
[39]
Ichiro Takeuchi, Quoc V. Le, Timothy D. Sears, and Alexander J. Smola. Nonparametric quantile estimation. Journal of Machine Learning Research , 7:1231 – 1264, 2006. Cited by: 319
work page 2006
-
[40]
A review on quantile regression for stochastic computer experiments
L \'e onard Torossian, Victor Picheny, Robert Faivre, and Aur \'e lien Garivier. A review on quantile regression for stochastic computer experiments. Reliability Engineering & System Safety , 201:106858, 2020
work page 2020
-
[41]
Continuity of generalized entropy
Aolin Xu. Continuity of generalized entropy. In 2020 IEEE International Symposium on Information Theory (ISIT) , pages 2246--2251, 2020
work page 2020
-
[42]
Regularized simultaneous model selection in multiple quantiles regression
Hui Zou and Ming Yuan. Regularized simultaneous model selection in multiple quantiles regression. Computational Statistics & Data Analysis , 52(12):5296--5304, 2008
work page 2008
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.