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Human Evaluation
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pyCD: A Unified Benchmark for Reliable Evaluation of Cognitive Diagnosis Models
Youheng Bai, Xueyi Li, Tengteng Cheng, Mingliang Hou, Teng Guo, Jiaqi Zheng, Zitao Liu
Cognitive diagnosis (CD) infers students' mastery of knowledge components (KCs) from their responses, supporting personalized feedback and exercise recommendation. Cognitive diagnosis models (CDMs) are often ranked by response-prediction AUC under inconsistent experimental protocols, while their KC-level mastery profiles are not consistently audited under a shared protocol. We introduce \texttt{pyCD}, a unified benchmark of eleven CDMs on six public datasets that fixes preprocessing, splits, hyperparameter search, and stopping rules; the benchmark reports KC-level diagnostic metrics for learned mastery alongside standard prediction metrics. Two findings show that gains in AUC do not translate into gains in diagnostic quality. First, the AUC leaderboard is sharply compressed and sensitive to protocol choices: modern CDMs often cluster within $0.005$--$0.020$ AUC, with the per-dataset best non-IRT CDM improving over IRT by only $0.017$ AUC on average; removing validation-AUC early stopping can shift AUC by up to $0.13$ on individual cells. Second, the AUC gaps that remain do not reliably transfer into diagnosis: the top-1 AUC model is typically outside the top-3 by KC-level diagnostic agreement (DOA). The same mismatch extends to exercise difficulty: against Junyi's human pairwise difficulty ratings, learned CDM difficulty parameters rank worse than both an empirical accuracy-based baseline and zero-shot LLMs given only exercise titles. CDM evaluations should therefore report diagnostic outputs directly rather than infer them from predictive gains; \texttt{pyCD} provides a unified protocol for doing so. Code, splits, and configurations are available at \url{https://anonymous.4open.science/r/pyCD-NeurIPS2026-60B8}.
WorldReasonBench: Human-Aligned Stress Testing of Video Generators as Future World-State Predictors
Keming Wu, Yijing Cui, Wenhan Xue, Qijie Wang, Xuan Luo, ZhiYuan Feng, Zuhao Yang, Sudong Wang, Sicong Jiang, Haowei Zhu, Zihan Wang, Ping Nie, Wenhu Chen, Bin Wang
Commercial video generation systems such as Seedance2.0 and Veo3.1 have rapidly improved, strengthening the view that video generators may be evolving into "world simulators." Yet the community still lacks a benchmark that directly tests whether a model can reason about how an observed world should evolve over time. We introduce WorldReasonBench, which reframes video generation evaluation as world-state prediction: given an initial state and an action, can a model generate a future video whose state evolution remains physically, socially, logically, and informationally consistent? WorldReasonBench contains 436 curated test cases with structured ground-truth QA annotations spanning four reasoning dimensions and 22 subcategories. We evaluate generated videos with a human-aligned two-part methodology: Process-aware Reasoning Verification uses structured QA and reasoning-phase diagnostics to detect temporal and causal failures, while Multi-dimensional Quality Assessment scores reasoning quality, temporal consistency, and visual aesthetics for ranking and reward modeling. We further introduce WorldRewardBench, a preference benchmark with approximately 6K expert-annotated pairs over 1.4K videos, supporting pair-wise and point-wise reward-model evaluation. Across modern video generators, our results expose a persistent gap between visual plausibility and world reasoning: videos can look convincing while failing dynamics, causality, or information preservation. We will release our benchmarks and evaluation toolkit to support community research on genuinely world-aware video generation.
When Are Predictions Enough? An Evaluation Protocol for Frozen Expert Composition
Alessandro Pereira, Keith J Ransom, Lewis Mitchell
Practitioners often combine independently trained models as a fixed pool of frozen experts. Standard combination methods, such as voting, averaging, or stacking, rely on final predictions, amounting to a few scalars per expert, and discard potentially richer cross-expert information found in the penultimate representations. An alternative is to combine these models in feature space. Whether this yields a meaningful improvement depends heavily on the evaluation design. Informal assessments on the same data can support materially different conclusions depending on baseline strength, overlap control, reporting granularity, and pool construction. We argue that auditing the sensitivity of evaluation outcomes to these design choices is critical for the effective composition of expert models. To address these sensitivities, we propose a four-part evaluation protocol: (1) a baseline ladder for prediction-space (PS) models; (2) a deterministic feature-space (FS) anchor plus a higher-capacity cross-check; (3) axis-isolated pools to disentangle performance gains; and (4) grouped evaluation with overlap-aware controls. Applying our protocol to 21 frozen deepfake detectors from DF40 (Yan et al., 2024), we find that a 10K-parameter logistic regression on raw concatenated features outperforms the strongest PS baseline by +0.123 AUROC on an architecture-diverse pool (generator-level bootstrap 95% CI [+0.078, +0.174]). Crucially, the higher-capacity cross-check (a 3.5M-parameter feature-space MLP) adds only +0.004 AUROC, suggesting that the gain arises from the richer feature interface rather than from combiner complexity. Prediction-space models suffice when individual expert performance is high but fall short in architecture-diverse, high-bottleneck pools. Our primary contribution is an evaluation-design audit showing that, on this benchmark and expert pool, relaxing any of these controls risks overstating the apparent FS advantage or creating the illusion of a gain that fails to hold across data subgroups. Our findings demonstrate that, without rigorous controls, the same data can support multiple, sometimes spurious, conclusions.
Verifier Choice is a Benchmark Design Variable: Auditing Structural Counting Evaluation in Text-to-Image Models
Shurun Li, Michael H Wang, Haibo Zeng, Long Wang
Automatic evaluation is now central to text-to-image benchmarking, but the verifier that converts generated images into scores is often treated as an implementation detail. We argue that this is unsafe: an automatic benchmark score is a property of the image generator, prompt distribution, verifier, verifier-use protocol, and scoring rule, not of the generator alone. We study this issue in structural counting, a controlled setting where human-visible counts can be audited and where both instance-level object counts and parent-bound substructure counts arise naturally. We construct a verifier-centric audit suite over seven counting objects: cell phones, chairs, and traffic lights for object counting, and clover leaflets, dresser drawer fronts, power-strip sockets, and turbine blades for substructure counting. Across 6,240 generated images from Qwen-Image-2512 and FLUX.2-dev, we compare open MLLM verifiers under count-only, reject-aware, zero-shot and few-shot protocols, plus TIFA-like target-query variants and targeted frontier closed-model sanity checks on two hard objects. We also compare MLLMs with a detector baseline. On a balanced 2,280-image evaluation split, Qwen3.5-27B with few-shot reject/count achieves the best image-level agreement among open verifiers ($\kappa=0.754$) with a small aggregate score gap ($+1.54\text{pp}$), but changing the protocol, model size, or generator distribution can shift automatic scores by tens of points. Targeted GPT-5.5 and Claude Opus 4.7 checks do not remove the failure modes: GPT-5.5 still has only 59.92\% clover valid-count fidelity, while Claude Opus 4.7 has lower same-slice agreement ($\kappa=0.432$). We propose reporting a factorized verifier reliability profile---aggregate score gap, image-level agreement, valid-image count fidelity, rejection behavior, output compliance, and directional bias---rather than a single automatic benchmark score.
VTBench: Disentangled and Human-Aligned Evaluation for Image-Based Virtual Try-on
Donghao Luo, Yujie Liang, Caoshuo Li, Xiaobin Hu, Zuxuan Wu, Yanwei Fu
While virtual try-on has achieved significant progress, evaluating these models towards real-world scenarios remains a challenge: unpaired metrics (FID/KID) miss task-specific dimensions such as texture and consistency, and most test sets are limited to indoor scenarios. To address these needs, we introduce the Virtual Try-on Benchmark (VTBench), the first-ever hierarchical try-on benchmark suite that systematically decomposes virtual image try-on into hierarchical, disentangled dimensions, each equipped with tailored test sets and evaluation criteria. VTBench exhibits three key advantages: 1) Multi-Dimensional Evaluation Framework: The benchmark defines three top-level dimensions (General Image Quality, Garment Preservation, Auxiliary Consistency) and six fine-grained dimensions (Distributional Fidelity, Aesthetics, Texture Fidelity, Cross-Category Plausibility, Background Consistency, and Hand Consistency). Granular evaluation metrics and targeted test sets pinpoint model capabilities and limitations across diverse, challenging scenarios. 2) Human Alignment: Human preference annotations are provided for the five image-level dimensions, ensuring the benchmark's alignment with perceptual quality. 3) Valuable Insights: Beyond standard indoor settings, we analyze model performance variations across dimensions and investigate the disparity between indoor and real-world try-on scenarios. To foster the field of virtual try-on towards challenging real-world scenarios, VTBench will be open-sourced, including all datasets and evaluation algorithms.
VIPBench: A Human-Aligned Benchmark for Voice Identity Perception in the Age of Voice Cloning
Xudong Tang, Matthew Groh
Speaker identification benchmarks evaluate how accurately a model can predict a ground-truth speaker label for a given utterance, treating voice identity as a property of the recording's producer. However, these benchmarks do not test whether a model aligns with human perception of voice identity. Whether a human would hear two voices and interpret them as the same speaker or not has consequences for intellectual property rights, cybersecurity, and everyday life. We make two contributions. First, we introduce the Voice Identity Perception benchmark (VIPBench), built from the identity judgments of English-speaking crowdworkers on stratified celebrity voice pairs. VIPBench consists of 124,876 same/different identity judgments from 1,290 participants on 9,800 voice pairs across 100 speakers, spanning real recordings, AI voice clones generated by a state-of-the-art Text-to-Speech (TTS) system, and continuously morphed voices. Our second contribution is to define four evaluation tasks: predicting the listener same-speaker agreement rate; binary same/different classification against the majority listener vote, evaluated for both ranking and calibration; alignment between the model's and listeners' speaker-similarity structures; and whether a predictor fit on real speech still works on voice clones and morphs. We report baselines for ten publicly available speech representations. We find that the perception target re-orders model rankings relative to metadata: supervised embeddings (trained on metadata speaker labels) still outperform self-supervised models (which learn voice structure without identity supervision), and no model reaches the noise ceiling. VIPBench enables systematic evaluation of speaker representations against human voice-identity perception across real, cloned, and morphed speech, motivating speaker models trained on perceptual judgments directly.
The Deadline Effect: Identifying and Correcting Temporal Bias in Human Evaluation
Shiyan Liu
Submission timing in human evaluation systems is universally treated as an irrelevant detail. We identify a systematic temporal leniency bias: across 129,023 reviews spanning three consecutive years of a large-scale ML venue, evaluators submitting closer to the deadline assign higher within-paper scores and produce less thorough assessments. The pattern holds in all 15 robustness specifications across all three years, and early evaluators achieve measurably lower Brier scores ($\Delta \approx 0.005$--$0.006$, stable across years). We propose two complementary corrections. Optimal Timing-Calibrated Aggregation (OTCA) derives a linear weight function $w(t) = a^{\star} t + 1$ by minimising paper-level decision loss, significantly outperforming heuristic alternatives (McNemar $\chi^2 = 46.3$, $p < 0.001$). Adversarial Temporal Debiasing (ATD) learns timing-invariant representations via Gradient Reversal, reducing timing discriminability by $37.4\\%$ while preserving predictive utility. Combined in a joint scheme, the two methods improve borderline decision accuracy by up to $11.25\\%$ over uniform averaging (McNemar $p < 0.001$), consistently across all three years. Both methods require only submission timestamps, already logged by every major evaluation platform, making deployment cost-free.
Select Smarter, Not More? Prompt-Aware Evaluation Scheduling with Submodular Guarantees
Haoyue Liu, Xiaoyu Ma, Yiwen Li, Zhichao Wang, Shuguang Cui, Xiaoying Tang
Prompt optimizers invest heavily in how to generate better prompts, yet pay almost no attention to which examples they use to judge them. This evaluation subset directly shapes every feedback signal that the optimizer receives, while existing methods either fix it before optimization begins (principled but agnostic to the evolving prompt population) or adapt it heuristically (flexible but unstable). We bridge this gap by constructing an online adaptive testing problem: Prompts are examinees, training examples are test items, and the scheduler selects items that best discriminate among the strongest candidates. We introduce POES (Prompt-Aware Online Evaluation Scheduling), whose monotone submodular objective combines discrimination, coverage, and bounded subset updates, yielding a $(1-1/e)$ cold-start guarantee and a warm-start tracking bound under bounded inter-round drift. Across a 35-task APO suite plus 57 MMLU subjects and 6 optimizer-model configurations, POES achieves the highest mean accuracy in every configuration, improving over the best baseline by +3.0 pp to +7.8 pp. Notably, the achieved gains concentrate on tasks where baselines still have headroom to improve, vanishing where methods saturate, suggesting that what you evaluate on matters most precisely when there is a signal to extract.
SR-Prominence: A Crowdsourced Protocol and Dataset Suite for Perceptually-Weighted Super-Resolution Artifact Evaluation
Ivan Molodetskikh, Kirill Malyshev, Mark Mirgaleev, Nikita Zagainov, Evgeney Bogatyrev, Dmitriy Vatolin
Modern image super-resolution methods generate detailed, visually appealing results, but they often introduce visual artifacts: unnatural patterns and texture distortions that degrade perceived quality. These defects vary widely in perceptual impact—some are barely noticeable, while others are highly disturbing—yet existing detection methods treat them equally. We propose artifact prominence as an evaluative target, defined as the fraction of viewers who judge a highlighted region to contain a noticeable artifact. We design a crowdsourced annotation protocol and construct SR-Prominence, a dataset suite containing 3,935 artifact masks from DeSRA, Open Images, Urban100, and a realistic no-ground-truth Urban100-HR setting, annotated with prominence. Re-annotating DeSRA reveals that 48.2% of its in-lab binary artifacts are not noticed by a majority of viewers. Across the suite, we audit SR artifact detectors, image-quality metrics, and SR methods. We find that classical full-reference metrics, especially SSIM and DISTS, provide surprisingly strong localized prominence signals, whereas no-reference IQA methods and specialized artifact detectors often fail to generalize across datasets and reference settings. SR-Prominence is released with an objective scoring protocol that allows new metrics to be benchmarked on our suite without further crowdsourcing. Together, the data and protocols enable SR artifact evaluation to move from binary defect presence toward perceptual impact.
SALART-VQA: Diagnosing Whether VLMs Understand Salient Artifacts in Generated Images
Xiaoxiao Sun, Ruotian Zhang, JUNZHE HUANG, James Burgess, Serena Yeung-Levy
Vision-language models (VLMs) are increasingly used to detect whether AI-generated images contain visible artifacts, yet their ability to analyze such artifacts remains poorly understood. A correct image-level decision can still hide important failures: a model may correctly flag an artifact while relying on the wrong visual cue, selecting the wrong region, or describing a defect that the image does not support. To evaluate these behaviors directly, we introduce SalArt-VQA, a diagnostic benchmark for fine-grained salient artifact understanding in AI-generated images. SalArt-VQA contains 950 images and 3,681 human-authored multiple-choice questions spanning artifact images, matched real reference images, and paired generated reference images. Four aligned question types evaluate presence detection, semantic localization, spatial grounding, and evidence-grounded defect identification, while the reference splits test calibration and abstention when the annotated defect is absent. Across 20 VLMs, SalArt-VQA reveals failures that image-level detection accuracy hides: the strongest model reaches 99.37% detection recall on artifact images but answers all four artifact-side questions correctly on only 53.26% of images. Comparing artifact images with defect-absent references reveals a sensitivity–calibration tradeoff: sensitive models often make unsupported artifact claims, while conservative models avoid false alarms largely by missing real artifacts. These results show that high artifact detection accuracy alone does not imply grounded artifact understanding. SalArt-VQA exposes these hidden failure modes and provides a fine-grained evaluation of whether VLM artifact claims are supported by local visual evidence.
Rethinking XAI Evaluation: A Human-Centered Audit of Shapley Benchmarks in High-Stakes Settings
Inês Oliveira e Silva, Sérgio Jesus, Iker Perez, Rita P. Ribeiro, Carlos Soares, Hugo Ferreira, Pedro Bizarro
Shapley values are a cornerstone of explainable AI, yet their proliferation into competing formulations has created a fragmented landscape with little consensus on practical deployment. While theoretical differences are well-documented, evaluation remains reliant on quantitative proxies whose alignment with human utility is unverified. In this work, we use a unified amortized framework to isolate semantic differences between eight Shapley variants under the low-latency constraints of operational risk workflows. We conduct a large-scale empirical evaluation across four risk datasets and a realistic fraud-detection environment involving professional analysts and 3,735 case reviews. Our results reveal a fundamental misalignment: standard quantitative metrics, such as sparsity and faithfulness, are decoupled from human-perceived clarity and decision utility. Furthermore, while no formulation improved objective analyst performance, explanations consistently increased decision confidence, signaling a critical risk of automation bias and overconfidence in high-stakes settings. These findings demonstrate that current evaluation proxies are insufficient for predicting human impact, motivating our release of interaction measurements to support research into behaviorally grounded XAI evaluation.
Reporting Practice Matters: The Impact of Reference Choice on Chest X-ray Report Evaluation
Daniel P. Jeong, Charles Q Li, Hossein Hosseiny, Nitya M Bhalla, Fatma U Morency, Pradeep Ravikumar, Zachary Lipton, Michael Oberst
Radiologists follow heterogeneous reporting practices. Two radiologists examining the same image and identifying the same clinical findings might nevertheless compose superficially distinct reports, varying in terminology, shorthand, formatting, and level of detail. These variations in reporting norms represent an under-appreciated obstacle in efforts to evaluate AI-based radiology report generation (RRG) models, where machine-generated reports are typically assessed based on their concordance with human-generated references. In this paper, we quantify the sensitivity of established evaluation metrics to variations in reporting practices, revealing impacts significant enough to alter the rankings of models. We introduce a radiologist-informed taxonomy of variations in radiology reporting practice and a method (ReRef) that rewrites reference reports along the axes of our taxonomy while preserving clinical interpretation. For instance, when comparing the performance of nine RRG models on MIMIC-CXR using the GREEN metric, condensing the discussion of normal findings in the reference reports causes Libra to drop from first place to third while CheXOne rises from third to first. Our results suggest that current metrics may fail to decouple clinical interpretation from conformity to reporting practices and that choosing the "right" references that accurately reflect the desired reporting practices can be important in practice. To support future research, we release MIMIC-CXR-Ext-ReRef, a radiologist-validated dataset of 120 (original, alternative) reference report pairs derived from MIMIC-CXR.
Post-Selection Distributional Model Evaluation
Amirmohammad Farzaneh, Osvaldo Simeone
Formal model evaluation methods typically certify that a model satisfies a prescribed target key performance indicator (KPI) level. However, in many applications, the relevant target KPI level may not be known a priori, and the user may instead wish to compare candidate models by analyzing the full trade-offs between performance and reliability achievable at test time by the models. This task, requiring the reliable estimate of the test-time KPI distributions, is made more complicated by the fact that the same data must often be used both to pre-select a subset of candidate models and to estimate their KPI distributions, causing a potential post-selection bias. In this work, we introduce post-selection distributional model evaluation (PS-DME), a general framework for statistically valid distributional model assessment after arbitrary data-dependent model pre-selection. Building on e-values, PS-DME controls post-selection false coverage rate (FCR) for the distributional KPI estimates and we establish explicit conditions under which it is provably more sample efficient than a baseline method based on sample splitting. Experiments on synthetic data, text-to-SQL decoding with large language models, and telecom network performance evaluation demonstrate that PS-DME enables reliable comparison of candidate configurations across a range of reliability levels, supporting the statistically reliable exploration of performance--reliability trade-offs.
PhyProbe: Rethinking Physical Consistency Evaluation in Generated Videos
Max Ku, Jiaojiao Fan, Zekun Hao, Francesco Ferroni, Heng Wang, Wenhu Chen, Ming-Yu Liu, Prithvijit Chattopadhyay
Evaluating the physical consistency of generated videos remains a fundamental challenge. Existing approaches rely on off-the-shelf vision-language models, which can often be myopic to physical dynamics, or fine-tuned evaluators trained on human annotations, which overfit to dataset-specific cues and fail to generalize. A key challenge is that existing supervision sources provide either relative ordering or absolute scores, but not both reliably and consistently across varied settings. To this end, we introduce PhyProbe, an evaluator that extracts features from a frozen pretrained spatio-temporal encoder and maps them to a scalar physical consistency violation score via a lightweight scoring head. PhyProbe is trained through a unified objective combining pairwise ranking, regression on noisy scalar annotations, and anchor-based calibration over a curated set of heterogeneous supervision sources. Experiments show that PhyProbe significantly outperforms prior methods on pairwise benchmarks spanning real–generated and generated–generated pairs under varying correspondence, including challenging settings where existing approaches degrade toward random performance. PhyProbe achieves strong correlation with human judgments, with close agreement between rank-based and linear metrics, indicating both reliable ordering and calibrated scores. Further, despite being trained solely for physical consistency, PhyProbe also performs competitively on human preference benchmarks: consistent with the observation that physics violations are entangled with broader quality degradations.
OmniMechanism Design for Human-AI Collaboration with Impressionable Minds
Tianwei Gao, Yifei Pang, Lunjia Hu, Kate Donahue, Lihua Lei, Vahid Tarokh, Zhun Deng
As AI systems are increasingly deployed in high-stakes domains such as healthcare, effectively integrating human expertise with AI outputs is critical for reliable decision-making. A substantial body of theoretical work studies optimal mechanisms for human-AI collaboration (HAC), focusing on when to involve humans and how to combine their expertise with AI predictions. However, these approaches largely overlook a key factor highlighted by empirical evidence: human judgments are impressionable and can vary depending on how AI outputs are presented. For example, when AI systems defer decisions to humans, revealing or withholding the AI prediction can significantly influence human judgments. Moreover, existing work neglects deployment-time variability, where conditions, particularly the cost of eliciting human input, may differ substantially from those observed during training. To address these challenges, we introduce a rigorous and theoretically grounded framework for human-AI collaboration, termed \emph{collaborative omnimechanism design}, based on a novel and computationally efficient contextual bandit variant of boosting for outcome indistinguishability. In particular, we reduce a calibration-type outcome indistinguishability condition to projected smooth calibration, providing novel time-efficiency result, bypassing the high-dimension curse induced by complicated collaboration methods. Our framework provides a principled characterization of human impressionability and introduces a unified optimization scheme that enables robust and adaptable decision-making across diverse query costs and evaluation objectives without retraining. We further validate our theoretical results through comprehensive experiments.
Off-Policy Evaluation of Large Language Models via Learned Semantic Bottleneck Embeddings
Younwoo Choi, Hadi Sheikhi, Leo Feng, Haanvid Lee
Evaluating large language models (LLMs) via online human feedback is prohibitively expensive and time-consuming. Off-policy evaluation (OPE) addresses this by estimating LLM policy performance from offline data. However, traditional OPE estimators such as Inverse Propensity Score (IPS) suffer from high variance. Marginalized IPS (MIPS) addresses this variance issue by reweighting the IPS weights via condensed semantic embeddings. However, MIPS assumes embeddings contain sufficient reward-predictive information, an assumption that off-the-shelf embeddings often fail to satisfy. To address this, in this paper, we propose Semantic Bottleneck Embedding (SBE), which learns representations for marginalized reweighting via a conditional information bottleneck, compressing reward-irrelevant information while preserving reward-predictive content to achieve both bias and variance reduction. Our objective targets minimizing the derived mean squared error upper bound of the resulting MIPS estimator. Empirically, evaluation on the HelpSteer2 and UltraFeedback datasets across Qwen, Gemma, and Llama policies show SBE-MIPS reduces MSE over prior baselines.
OdysSim: Building Foundation Models for Human Behavior Simulation
Xuhui Zhou, Weiwei Sun, Weihua Du, Jiarui Liu, Haojia Sun, Qianou Ma, Sherry Wu, Yiming Yang, Maarten Sap
Large language models are increasingly used as human simulators for interactive evaluation and social simulation, yet current post-training often produces homogeneous, overly helpful systems unlike real people, creating a behavioral Sim2Real gap that prompting alone cannot close. We present Odyssim, a large-scale open study of behavioral foundation models organized around SOUL, whose five capability Axes (CONV, SS, COG, ROLE, EVAL) jointly guide data curation and evaluation. We release three artifacts: (1) SOULIndex, a 23-task evaluation suite for human-behavior simulation; (2) OdysSim, a corpus of 21.4M interactions, approximately 10B tokens, from 63 public sources, unified into a conversational format and retrofitted with back-generated social contexts; and (3) an end-to-end recipe combining midtraining, task-specific RL with VFRL, and expert distillation into a single deployable model. On SOULIndex, OdysSim-8B achieves an average score of 62.4, comparable to frontier models such as GPT-5.5 (62.6), ranks first on 8 of 23 tasks, and outperforms prior open behavioral-simulation baselines by 14.2 points on average. We also identify and mitigate reward-hacking failures in judge-based behavioral RL, including judge manipulation and short-response collapse. We release the corpus, benchmark, recipes, and checkpoints.
OTROPE: Optimal Transport-based Robust Off-policy Evaluation for Large Language Models
Liner Xiang, Wenbo Zhang, Hengrui Cai
Reliable evaluation of large language models (LLMs) is essential for their development and deployment, yet is often costly, risky, and difficult to perform safely online. We study *off-policy evaluation* for LLMs, where limited human-labeled data from a behavior model are used to evaluate a newer target LLM. This setting is challenging because labels are scarce, behavior--target distribution shift is common, and response likelihoods are often unavailable for black-box LLMs. We propose the **O**ptimal **T**ransport-based **R**obust **O**ff-**P**olicy **E**valuation (**OTROPE**), a likelihood-free evaluation that performs *distributional correction* in a *semantic space* via optimal transport to align labeled behavior-policy samples with unlabeled target-policy samples. OTROPE combines corrected human-labeled residuals with proxy predictors, yielding a stable *doubly robust*-style evaluation without behavior-policy modeling or density-ratio estimation. We theoretically characterize why baseline evaluators fail under LLM distribution shift, and establish consistency and convergence rates for OTROPE when either the reweighted behavior distribution or the proxy predictor converges. Experiments on synthetic and real LLM evaluation tasks show that OTROPE consistently outperforms baselines while enabling ensembles of weaker LLM evaluators to approach and sometimes surpass stronger evaluators.
Leak-CURBER: A Leakage-Controlled Multimodal Evaluation Benchmark for Enzymatic Reaction Tasks
Adhil Ahmed P M Shums, Roshan Balaji, Nirav Bhatt
We present Leak-CURBER, the largest multimodal, leakage-controlled benchmark for evaluating machine learning and deep learning models for enzymatic reactions. Leak-CURBER standardizes data from 10 biochemical databases and curates datasets with multimodal inputs, metrics, and leakage-controlled splits for 4 tasks. The benchmark comprises 10 subtasks: prediction of reaction outcomes (2), enzyme function (2), kinetic parameters (3), and protein–ligand binding (3). Leak-CURBER establishes new evaluation protocols that control for train/validation/test overlap across protein sequence and structure, molecule string and structure, and reaction similarity, thereby exposing generalization failures of learning methods. Evaluating the state-of-the-art (SOTA) models on Leak-CURBER shows that their strong performance degrades sharply under these splits, often approaching random classification or retrieval performance, and near-zero regression performance. Leak-CURBER includes precomputed embeddings, continual benchmark releases, reproducible curation scripts, and a public leaderboard to support reliable comparison of enzymatic-reaction models.
Intra-Option Fitted Q-Evaluation: Evaluating Hierarchical Policies from Non-Hierarchical Data
Yunfu Deng, Josiah Hanna
Off-policy evaluation (OPE) estimates the expected return of a target policy from previously collected data without additional environment interaction. While OPE methods for flat Markovian policies are well studied, little work has addressed evaluating hierarchical policies in which a high-level policy selects temporally extended options that generate primitive actions until a termination condition is met. The primary existing approach applies per-decision importance sampling at the option level, but requires option-annotated trajectories and exhibits variance that grows with the horizon and action dimensionality. For non-hierarchical policies, fitted Q-evaluation (FQE) typically achieves lower error than importance sampling by leveraging the classic Bellman equation for policy evaluation; however, a naive extension of FQE to hierarchical policies results in a biased policy value estimate. In this paper, we introduce Intra-Option Fitted Q-Evaluation (IO-FQE), which estimates a value function in the augmented state-option space; this approach enables OPE of hierarchical policies even when we lack annotations of what option was ran in the data. We develop two continuous-action instantiations of IO-FQE and show on hierarchical continuous control tasks (AntMaze navigation and OGBench Puzzle manipulation) that IO-FQE eliminates the bias incurred by a naive application of FQE to hierarchical policies and substantially lowers mean squared-error compared to option-level importance sampling.