Multi-Turn Long-Form Question Answering (MT-LFQA) is a key application paradigm of Large Language Models (LLMs) in knowledge-intensive domains. However, existing benchmarks are limited to single-turn dialogue, while multi-turn dialogue benchmarks typically assess other orthogonal capabilities rather than knowledge-intensive factuality. To bridge this critical gap, we introduce KnowMT-Bench, a new benchmark designed to systematically evaluate MT-LFQA for LLMs across knowledge-intensive fields, including medicine, finance, and law. To faithfully assess the model's real-world performance, KnowMT-Bench employs a dynamic evaluation setting where models generate their own multi-turn dialogue histories given logically progressive question sequences. Our experiments on a diverse suite of LLMs show a clear degradation in both factual capability and information delivery efficiency in multi-turn dialogue. We further probe the underlying causes and investigate mitigation strategies spanning domain-specific finetuning, active context denoising, and RAG. The results show domain-dependent gains from finetuning, while active context denoising and RAG more consistently mitigate these issues, with RAG notably reversing this performance degradation. These findings underscore the importance of our benchmark for evaluating LLMs' conversational factual capabilities in real-world applications. Code and data are publicly available.\footnote{https://github.com/Sven-LI-sankyuu/KnowMT-Bench}
Figures & tables
Benchmark
# Avg. Tokens
MT
OD
CoQA ( Reddy et al., 2019 )
2.52
✓
✗
QASA ( Lee et al., 2023 )
50
✗
✗
K-QA ( Manes et al., 2024 )
119.89
✗
✓
MedLFQA ( Jeong et al., 2024 )
132.86
✗
✓
FintextQA ( Chen et al., 2024b )
75 *
✗
✓
KnowMT-Bench (ours)
95.15
✓
✓
Table 1: Comparison of KnowMT-Bench with existing QA benchmarks. # Avg. Tokens refer to the token counts of the ground truth answer, computed by the GPT-4o tokenizer. * : FintextQA is partially open-sourced; we report the 75-word value from their paper. MT denotes Multi-Turn, and OD refers to Open-Domain.
Figure 1: Single- vs. Multi-Turn LFQA on Llama-3.3-70B-Instruct; correct , irrelevant , and faulty statements.
Figure 2: Overview of the two-stage natural language inference-based evaluation. Here, GTA refers to G round T ruth A nswer, and the detailed prompts for evaluation are provided in Appendix J .
Figure 3: LLMs’ performance on factual capability and information delivery efficiency.
Figure 4: Effects of dialogue length on multi-turn performance across dialogue turns and context length.
Figure 5: Impact of manually annotated gold context on Qwen-2.5-7B .
Figure 6: Performance of GPT-4o under different types of controlled dialogue-history noise.
Finance
Non-finance
Model
Sf (%) ↑
Sh (%) ↓
Df↓
Dh↑
Sf (%) ↑
Sh (%) ↓
Df↓
Dh↑
Qwen-2.5-7B
16.50
2.29
376.19
616.21
21.87
4.26
361.73
575.38
14.60
2.12
578.12
888.26
19.52
4.84
524.34
815.99
Fin-R1
14.51
2.19
568.49
895.72
22.52
4.76
487.90
831.48
13.39
3.53
511.55
825.01
20.08
4.85
467.26
802.78
Medical
Non-medical
Table 2: Results across different domains. Underlined values denote improvements over the base model under the same domain and turn setting. White rows indicate single-turn results, while gray rows indicate multi-turn results.
Setting
Sf (%) ↑
Sh (%) ↓
Df↓
Dh↑
w/o RAG
Original
19.86
3.52
367.15
590.67
Original
17.68
3.82
544.48
843.06
w/ RAG
Base
40.77
1.87
193.70
575.75
Base
40.19
2.27
304.82
888.61
Table 3: Comparison of w/o versus w/ RAG on Qwen-2.5-7B . White rows indicate single-turn settings , while gray rows indicate multi-turn settings . Bold numbers highlight the best results of the multi-turn RAG setting. Underlined values denote improvements over the baseline under the same turn setting.
Strategy
Sf (%) ↑
Sh (%) ↓
Df↓
Dh↑
Baselines
Original
22.91
2.77
365
683
Original
22.05
3.12
434
743
Interventions
+ Simple Prompt
21.89
3.05
417
764
+ Summarization
24.05
3.28
259
419
Table 4: Performance comparison of Qwen2.5-32B with prompt-based mitigation strategies. Gray and white rows indicate as above. Underlined values denote improvements to the multi-turn baseline.
Appendix figures & tables27 assets
Supplementary material from the paper’s appendix.
Appendix
Benchmark
# Avg. Length
# Avg. Turns
Multi-turn
Long-Form
Open-Domain
QuAC ( Choi et al., 2018 )
14.6 t
7.2
✓
✗
✗
CoQA ( Reddy et al., 2019 )
2.52 t
15.97
✓
✗
✗
DoQA ( Campos et al., 2020 )
12.99 t
4.48
✓
✗
✗
Doc2Dial ( Feng et al., 2020 )
21 t
12
✓
✗
✗
MultiDoc2Dial ( Feng et al., 2021 )
21.6 t
6.36
✓
✗
✗
ConvFinQA ( Chen et al., 2022 )
-
3.67
✓
✗
✗
Appendix
Table 5: Conversational QA and LFQA benchmark. Columns show average ground-truth length, average number of turns, and whether dialogs are multi-turn, answers are long-form, and the task is open-domain (✓=yes, ✗=no). Notation: t = tokens, w = words, c = Chinese characters, -=not provided in the original paper.
Figure 7: Overview of the dataset construction process
Metric
Dimension
Meaning
Direction
Sf
Factuality
Factual F1 over supported facts and generated claims
Higher is better
Sh
Reliability
Hallucination F1 over contradicted facts and claims
Lower is better
Df
Efficiency
Token cost per correctly entailed fact
Lower is better
Dh
Efficiency
Token cost per contradicted fact
Higher means sparser errors
Appendix
Table 6: Summary of the main evaluation metrics.
Figure 8: Financial topics and turn-count distribution.
Model
Accuracy
F1
Precision
Recall
Qwen-2.5-14B
0.83
0.84
0.84
0.83
GPT-4o
0.81
0.82
0.84
0.81
DeepSeek-V3
0.76
0.78
0.84
0.76
Appendix
Table 7: Performance comparison on the Factual Consistency Judgment stage.
Model
Acc.
F1
Prec.
Rec.
SMAPE(%)
OR(%)
DS-V3
0.85
0.85
0.87
0.85
13.12
6.34
L3-8B
0.84
0.85
0.86
0.84
20.66
2.54
GPT-4o
0.83
0.83
0.83
0.83
19.70
7.52
Q2.5-14B
0.81
0.81
0.81
0.81
18.10
5.90
Appendix
Table 8: Performance breakdown per model, as judged by the Qwen-2.5-14B evaluator. OR refers to Omission Rate.
Model
DS-V3
L3-8B
GPT-4o
Q2.5-14B
DS-V3
-
.761 ns
.445 ns
.183 ns
L3-8B
.761 ns
-
.674 ns
.347 ns
GPT-4o
.445 ns
.674 ns
-
.602 ns
Q2.5-14B
.183 ns
.347 ns
.602 ns
-
Appendix
Table 9: Pairwise significance tests on model accuracy for evaluator impartiality. We report p-values from Mann-Whitney U tests. Note: ns denotes p ≥ 0.01.
Model
DS-V3
L3-8B
GPT-4o
Q2.5-14B
DS-V3
-
.477 ns
.237 ns
.104 ns
L3-8B
.477 ns
-
.086 ns
.030 ns
GPT-4o
.237 ns
.086 ns
-
.841 ns
Q2.5-14B
.104 ns
.030 ns
.841 ns
-
Appendix
Table 10: Pairwise significance tests (p-values from Mann-Whitney U tests) on model SMAPE for Decomposer. Note: ns denotes p ≥ 0.01.
Figure 9: Human validation of our evaluation pipeline. ( left ) Alignment between LLM-based and human-annotated atomic decompositions. ( right ) Alignment between LLM-based and human annotations for factual consistency judgments.
OR
Model (Mode)
Sf
GPT-4o Eval (Rank)
GPT-4o Decomp (Rank)
1
GPT-4o (Single)
28.99%
38.06% (1)
29.54% (1)
2
GPT-4o (Multi)
28.08%
37.86% (2)
29.24% (2)
3
DeepSeek-V3 (Single)
24.33%
33.82% (3)
24.51% (3)
4
Qwen-2.5-72B (Single)
24.30%
32.37% (5)
24.47% (4)
5
Llama-3.3-70B (Single)
24.06%
32.95% (4)
24.41% (5)
6
Llama-3.3-70B (Multi)
21.37%
29.26% (6)
21.50% (6)
Appendix
Table 11: Model Ranking ( Sf ) Consistency across Evaluators and Decomposer Variants. OR refers to Original Rank.
Model
Setting
Configuration
Sf (%)
Sh (%)
Df
Dh
GPT-4o
Single
Original
28.99
2.29
226
505
GPT-4o
Single
w/ GPT-4o Eval
38.06
3.36
179
434
GPT-4o
Single
w/ GPT-4o Decomp
29.54
2.55
226
507
GPT-4o
Multi
Original
28.08
2.47
255
553
GPT-4o
Multi
w/ GPT-4o Eval
37.86
3.11
214
532
GPT-4o
Multi
w/ GPT-4o Decomp
29.24
2.26
253
495
Appendix
Table 12: Cross-Model Validation – Detailed Metrics for Evaluator and Decomposer Variants.
Dataset
Logical
Goal
Transition
Overall
Confusion
Coherence
Clarity
Naturalness
Mean
Factor (CF)
StructFlowBench ( Li et al., 2025 )
4.78
4.46
4.18
4.47
0.82
MT-Bench-101 ( Bai et al., 2024 )
4.50
4.52
4.50
4.51
0.74
KnowMT-Bench (Ours)
4.72
4.46
4.12
4.43
0.78
Appendix
Table 13: Results of the Complex Scenario Suitability Study. We compare KnowMT-Bench against StructFlowBench and MT-Bench-101 across three qualitative dimensions and the composite Confusion Factor (CF). All scores are on a 1-5 scale except for CF, which is a ratio.
Factuality
Hallucination
Efficiency
Model
Rf (%) ↑
Pf (%) ↑
Sf (%) ↑
Rm (%) ↓
Pfc (%) ↓
Sh (%) ↓
Df↓
Dh↑
Single-turn
Gemini-2.5-Pro
56.95
18.10
23.40
11.30
3.33
3.03
674
1614
Gemini-3.1-Pro
57.37
24.27
28.24
7.71
3.39
2.37
280
706
GPT-4o
41.94
32.22
28.99
6.97
3.47
2.29
226
505
GPT-4o-mini
39.49
30.72
26.89
6.75
3.99
2.38
255
545
Appendix
Table 14: Results for all models. Sections explicitly indicate Single-turn , Multi-turn , and the separate Diff block (Multi vs. Single). Bold values mark, within each block , the best score per column (for ↑ higher is better; for ↓ lower is better). Green in Diff indicates improvement and red indicates degradation.
Figure 10: Comparison between standard multi-turn and a concatenated-history setting.
Figure 11: Performance degradation under controlled noise, comparing standard multi-turn and concatenated-history settings.
Figure 12: Bidirectional history substitution experiment between a strong model (GPT-4o) and a weaker model (Qwen-2.5-7B). It also underscores that our dynamic evaluation setting more faithfully captures real model performance.
Figure 13: Model performance mapped onto the four-quadrant framework. The x-axis captures overall factuality, derived from the correlation between Sf and Sh . The y-axis measures performance against the efficiency trade-off baseline, derived from the correlation between Df and Dh .
N-gram Based Metrics
Our Proposed Core Metrics
Model
BLEU−4↑
R−1↑
R−2↑
R−L↑
Sf (%) ↑
Sh (%) ↓
Df↓
Dh↑
Single-turn
Gemini-2.5-Pro
1.51
13.33
3.72
12.43
23.40
3.03
674
1614
Gemini-3.1-Pro
3.76
20.44
6.87
18.65
28.24
2.37
280
706
GPT-4o
5.43
25.98
8.65
23.53
28.99
2.29
226
505
GPT-4o-mini
4.79
24.98
7.89
22.55
26.89
2.38
255
545
Appendix
Table 15: Comparison of model performance using traditional n-gram-based metrics and our proposed core metrics. This table provides the detailed numerical results that complement the scatter plot analysis. Green indicates improvement, while red indicates degradation.
Metric
Correct & significant
Correct & not significant
Opposite & significant
Opposite & not significant
Sf
9/13
3/13
0/13
1/13
Sh
3/13
8/13
0/13
2/13
Df
11/13
1/13
0/13
1/13
Dh
10/13
0/13
0/13
3/13
Appendix
Table 16: Overall results of the Wilcoxon signed-rank tests for Figure 3. Here, “Correct” means that the observed difference between Multi-turn and Single-turn is aligned with the pre-defined expected direction: Multi-turn < Single-turn for Sf (degradation in factuality) and Multi-turn > Single-turn for Sh and Df (degradation in hallucination and efficiency for correct facts) as well as for Dh (an improvement, i.e., larger token cost per hallucinated fact). “Significant” means one-sided p<0.05 . Most models move in the expected direction and are significant on Sf , Df , and Dh , whereas for Sh the direction is usually correct but the significance is weaker, mainly because Sh values are close to 0 for many models under both settings.
Model
MT mean
ST mean
Diff (M-S)
Fit expectation
p -value (one-sided)
Significance
Gemini-2.5-Pro
0.22
0.23
-0.01
Yes
0.02
Gemini-3.1-Pro
0.28
0.28
-0.00
Yes
0.33
GPT-4o
0.28
0.29
-0.01
Yes
0.08
GPT-4o-mini
0.26
0.27
-0.01
Yes
0.02
DeepSeek-R1
0.20
0.22
-0.02
Yes
0.01
**
DeepSeek-V3
0.19
0.24
-0.05
Yes
0.00
Appendix
Table 17: Wilcoxon signed-rank test results for Sf (one-sided). The expected direction is Multi-turn < Single-turn. The column “Aligned with expectation?” indicates whether the mean difference between Multi-turn and Single-turn follows this expected direction. The “Significance” column uses *, ** and *** to denote one-sided p<0.05 , p<0.01 and p<0.001 , respectively. MT and ST denote multi-turn and single-turn.
Model
MT mean
ST mean
Diff (M-S)
Fit expectation
p -value (one-sided)
Significance
Gemini-2.5-Pro
0.04
0.03
0.01
Yes
0.00
Gemini-3.1-Pro
0.02
0.02
-0.00
No
0.54
GPT-4o
0.02
0.02
0.00
Yes
0.24
GPT-4o-mini
0.03
0.02
0.00
Yes
0.08
DeepSeek-R1
0.04
0.04
0.00
Yes
0.17
DeepSeek-V3
0.03
0.03
0.00
Yes
0.22
Appendix
Table 18: Wilcoxon signed-rank test results for Sh (one-sided). The expected direction is Multi-turn > Single-turn. The column “Aligned with expectation?” indicates whether the mean difference between Multi-turn and Single-turn follows this expected direction. The “Significance” column uses *, ** and *** to denote one-sided p<0.05 , p<0.01 and p<0.001 , respectively. MT and ST denote multi-turn and single-turn.
Model
MT mean
ST mean
Diff (M-S)
Fit expectation
p -value (one-sided)
Significance
Gemini-2.5-Pro
697.13
673.89
23.24
Yes
1.00
Gemini-3.1-Pro
302.54
280.41
22.12
Yes
0.00
GPT-4o
255.22
226.20
29.02
Yes
0.00
GPT-4o-mini
343.61
255.35
88.26
Yes
0.00
DeepSeek-R1
626.28
604.11
22.17
Yes
0.01
**
DeepSeek-V3
443.92
339.39
104.52
Yes
0.00
Appendix
Table 19: Wilcoxon signed-rank test results for Df (one-sided). The expected direction is Multi-turn > Single-turn, corresponding to a degradation in efficiency for correct facts (more tokens per correct fact). The column “Aligned with expectation?” indicates whether the mean difference between Multi-turn and Single-turn follows this expected direction. The “Significance” column uses *, ** and *** to denote one-sided p<0.05 , p<0.01 and p<0.001 , respectively. MT and ST denote multi-turn and single-turn.
Model
MT mean
ST mean
Diff (M-S)
Fit expectation
p -value (one-sided)
Significance
Gemini-2.5-Pro
1403.42
1613.53
-210.10
No
1.00
Gemini-3.1-Pro
733.68
705.55
28.13
Yes
0.00
GPT-4o
552.83
504.97
47.86
Yes
0.00
GPT-4o-mini
782.07
545.17
236.90
Yes
0.00
DeepSeek-R1
1175.41
1363.99
-188.58
No
1.00
DeepSeek-V3
877.23
737.92
139.31
Yes
0.00
Appendix
Table 20: Wilcoxon signed-rank test results for Dh (one-sided). The expected direction is Multi-turn > Single-turn, which corresponds to a larger token cost per contradicted fact and hence sparser hallucinations per token (an improvement from a robustness perspective). The column “Aligned with expectation?” indicates whether the mean difference between Multi-turn and Single-turn follows this expected direction. The “Significance” column uses *, ** and *** to denote one-sided p<0.05 , p<0.01 and p<0.001 , respectively. MT and ST denote multi-turn and single-turn.
Setting
Sf (%) ↑
Sh (%) ↓
Df↓
Dh↑
QwQ-32B
21.34
2.76
526
918
QwQ-32B-2048
20.24
3.82
699
1545
QwQ-32B
19.31
3.91
468
810
QwQ-32B-2048
17.61
3.92
807
1532
Appendix
Table 21: Performance comparison of QwQ-32B and QwQ-32B-2048. White and gray rows indicate the single-turn and multi-turn setting, respectively.
Figure 14: Correlation between Sf and traditional lexical metrics. While a positive trend is observed, models optimized for CoT reasoning tend to be undervalued by n-gram metrics, potentially due to subtle stylistic differences in their final answers.
Figure 15: Visualization of contextual token importance. Green indicates tokens that positively contribute to the model’s response, while red indicates tokens with a negative influence.
Setting
Mode
Sf (%)
Sh (%)
Df
Dh
Original
Single-turn
19.86
3.52
367
591
Topic Drift
Single-turn
19.50
3.43
367
590
Original
Multi-turn
17.68
3.82
544
843
Topic Drift
Multi-turn
20.48
4.81
536
833
Appendix
Table 22: Impact of Topic Drift on Qwen-2.5-7B. We compare the standard setting against a "Topic Drift" setting where an unrelated question is prepended to the context.
Large Language Models (LLMs) have demonstrated impressive capabilities across various specialist domains and have been integrated into high-stakes areas such as medicine. However, as existing medical-related benchmarks rarely stress-test the long-context memory, interference robustness, and safety defense required in practice. To bridge this gap, we introduce MedMT-Bench, a challenging medical multi-turn instruction following benchmark that simulates the entire diagnosis and treatment process. We construct the benchmark via scene-by-scene data synthesis refined by manual expert editing, yielding 400 test cases that are highly consistent with real-world application scenarios. Each test case has an average of 22 rounds (maximum of 52 rounds), covering 5 types of difficult instruction following issues. For evaluation, we propose an LLM-as-judge protocol with instance-level rubrics and atomic test points, validated against expert annotations with a human-LLM agreement of 91.94%. We test 17 frontier models, all of which underperform on MedMT-Bench (overall accuracy below 60.00%), with the best model reaching 59.75%. MedMT-Bench can be an essential tool for driving future research towards safer and more reliable medical AI. The benchmark is available in https://openreview.net/attachment?id=aKyBCsPOHB&name=supplementary_material
Evaluating large language models (LLMs) as multi-turn conversational partners requires probing capabilities that single-turn benchmarks miss: persona consistency, evolving intent tracking, emotional dynamics, and goal completion. We introduce EYT-Bench, a human-centered benchmark built around a three-party decoupled design: a persona-grounded user simulator, a target model that separates intent perception from response generation, and an independent third-party LLM judge with optional multi-judge ensembling. Personas are sampled from public human-curated corpora, Nemotron-Personas-USA and PersonaMem-v2, rather than synthesized, reducing LLM-induced persona bias. EYT-Bench also introduces two trajectory-level metrics: embedding-based intent drift and final-intent completion rate (FICR), inspired by tau-bench. In a 17-target x 200-dialogue evaluation, EYT-Bench reveals four findings: (i) state-of-the-art closed- and open-source models are statistically close on subjective dimensions (empathy / persona / anthropomorphism vary within <= 0.3), but differ by up to 9x on objective intent tracking; (ii) reasoning ("thinking on") sharply improves objective tracking on long-context personas (+0.47-0.50 latent-intent accuracy on Gemma-4) while leaving subjective scores nearly unchanged; (iii) persona format dominates trajectory spread, with FICR saturating above 0.95 on Nemotron-USA but spreading from 0.53 to 0.88 on PersonaMem-v2; and (iv) the warm-up effect is robust on 16/17 models (one outlier, GPT-5.5, reverses the effect), with stable rankings across alpha in [0.05, 0.15]. A cross-judge ablation using deepseek-v4-pro confirms that target rankings and final-intent satisfaction are preserved across judges.
Jinglan Gong, Jiefan Lu, Hewei Guo +5
SenseTime Research · University of Science and Technology of China · Tsinghua University
Parametric knowledge in large language models (LLMs) is a cornerstone of their success, yet remains poorly understood. Existing knowledge benchmarks typically rely on predefined questions (e.g., "What is the birth date of M.L. King?"), evaluating only knowledge that benchmark designers explicitly choose to query, a problematic availability bias. In this paper, we introduce open knowledge evaluation, a new paradigm for benchmarking the stated knowledge of LLMs. Instead of asking narrow questions, it evaluates models on the knowledge they choose to surface in response to open-ended elicitation prompts (e.g., "Tell me everything you know about M.L. King"). This shifts the focus from predefined answer retrieval toward characterizing the knowledge models naturally express. We instantiate this paradigm with BeQu (Beyond Questions), a benchmark of 10,000 entities paired with reference corpora for statement verification. Using BeQu, we evaluate a broad range of language models and analyze the effects of reasoning effort, model scale, prompt format, and knowledge domain. Data and leaderboard are available on this work's GitHub repository and at ANONYMIZED.