FLAWS: A Benchmark for Error Identification and Localization in Scientific Papers
Organizations: Carnegie Mellon University
Abstract
The identification and localization of errors is a core task in peer review, yet the exponential growth of scientific output has made it increasingly difficult for human reviewers to reliably detect errors given the limited pool of experts. Recent advances in Large Language Models (LLMs) have sparked interest in their potential to support such evaluation tasks, from academic peer review to automated scientific assessment. However, despite the growing use of LLMs in review systems, their capabilities to pinpoint errors remain underexplored. In this work, we introduce Fault Localization Across Writing in Science (FLAWS), an automated benchmark consisting of 713 paper-error pairs designed to evaluate how effectively LLMs detect errors that undermine key claims in research papers. We construct the benchmark by systematically inserting claim-invalidating errors into peer-reviewed papers using LLMs, paired with an automated evaluation metric that measures whether models can identify and localize these errors. Developing such a benchmark presents unique challenges that we overcome: ensuring that the inserted errors are well-defined, challenging, and relevant to the content of the paper, avoiding artifacts that would make identification trivial, and designing a scalable, automated evaluation metric. On the resulting benchmark, we evaluate five frontier LLMs: Claude Sonnet 4.5, DeepSeek Reasoner v3.1, Gemini 2.5 Pro, GPT 5, and Grok 4. Among these, GPT 5 is the top-performing model, achieving 39.1% identification accuracy when k=10, where k is the number of top-ranked error text candidates generated by the LLM.
Figures & tables
| Identification Model | Rank | Score | Accuracy | |
|---|---|---|---|---|
| @k=3 | @k=10 | |||
| GPT 5 | 1 | 2.10 | 19.2% | 39.1% |
| DeepSeek Reasoner v3.1 | 2 | 1.90 | 16.3% | 35.2% |
| Grok 4 | 3 | 1.68 | 16.3% | 23.4% |
| Claude Sonnet 4.5 | 4 | 1.47 | 12.6% | 21.5% |
| Gemini 2.5 Pro | 5 | 1.41 | 15.7% | 19.8% |
| Model | Knowledge Cutoff Date |
|---|---|
| DeepSeek Reasoner v3.1 | July 2024 |
| GPT 5 | September 30, 2024 |
| Grok 4 | November 2024 |
| Gemini 2.5 Pro | January 2025 |
| Claude Sonnet 4.5 2 2 2 We initially experimented with Claude Sonnet 3.7 (knowledge cutoff: Nov 2024), but it frequently failed to detect any errors. We therefore opted for Claude Sonnet 4.5 , which exhibited stronger identification performance. While there is possible data leakage due to the March 2025 knowledge cutoff date, Claude Sonnet 4.5 has poor performance as found in Section 5.2 . | March 2025 |
| Insertion Model | Gemini 2.5 Pro | GPT 5 | ||
|---|---|---|---|---|
| # Papers | # Errors | # Papers | # Errors | |
| Claim Extraction | 623 | - | 623 | - |
| Error Generation | 623 (100%) | 4025 | 623 (100%) | 9154 |
| Filtering Invalid Errors | 623 (100%) | 4008 (99%) | 623 (100%) | 9105 (99%) |
| Filtering Easy Errors Stage 1, Easy Error Prompt Filter | 623 (100%) | 3373 (84%) | 552 (87%) | 1722 (19%) |
| (Filtering Easy Errors Stage 2, Hallucination Filter ) | 573 (92%) | 2971 (74%) | 476 (76%) | 1358 (15%) |
| Insertion | Size | Identification | k=1 | k=3 | k=6 | k=10 |
|---|---|---|---|---|---|---|
| Both | 713 | Claude Sonnet 4.5 | 0.052 | 0.126 | 0.201 | 0.215 |
| DeepSeek Reasoner v3.1 | 0.059 | 0.163 | 0.283 | 0.352 | ||
| Gemini 2.5 Pro | 0.066 | 0.157 | 0.194 | 0.198 | ||
| GPT 5 | 0.090 | 0.192 | 0.300 | 0.391 | ||
| Grok 4 | 0.088 | 0.163 | 0.215 | 0.234 | ||
| Gemini 2.5 Pro | 448 | Claude Sonnet 4.5 | 0.058 | 0.143 | 0.223 | 0.250 |
| Identification ( ) | ||||
|---|---|---|---|---|
| Claude Sonnet 4.5 | 0.25( 0.18) | 1.24( 0.12) | 1.76( 0.10) | 1.87( 0.10) |
| DeepSeek Reasoner v3.1 | 0.38( 0.23) | 1.54( 0.15) | 2.22( 0.13) | 2.56( 0.12) |
| Gemini 2.5 Pro | 0.51( 0.36) | 1.41( 0.25) | 1.53( 0.22) | 1.64( 0.21) |
| GPT 5 | 0.83( 0.24) | 1.73( 0.17) | 2.33( 0.14) | 2.76( 0.14) |
| Grok 4 | 0.82( 0.21) | 1.54( 0.15) | 1.84( 0.13) | 1.98( 0.13) |
| Insertion ( ) |
| Insertion Model | Identification Model | # Error Texts Candidates | ||
|---|---|---|---|---|
| Median | Mean | Std | ||
| Gemini 2.5 Pro | Claude Sonnet 4.5 | 5 | 5.41 | 1.48 |
| DeepSeek Reasoner v3.1 | 9 | 7.77 | 2.78 | |
| Gemini 2.5 Pro (insertion model) | 4 | 3.83 | 1.42 | |
| GPT 5 | 9 | 8.56 | 1.62 | |
| Grok 4 | 5 | 4.88 | 2.11 | |
Appendix figures & tables13 assets
Supplementary material from the paper’s appendix.
Appendix
| Label | Precision | Recall | F1 | Support |
|---|---|---|---|---|
| Not Identified | 0.94 | 0.90 | 0.92 | 148 |
| Identified | 0.69 | 0.79 | 0.73 | 42 |
| Accuracy | - | - | 0.88 | 190 |
| Label | Precision | Recall | F1 | Support |
|---|---|---|---|---|
| Not Identified | 0.89 | 0.90 | 0.90 | 148 |
| Identified | 0.63 | 0.62 | 0.63 | 42 |
| Accuracy | - | - | 0.84 | 190 |
| Label | Precision | Recall | F1 | Support |
|---|---|---|---|---|
| Not Identified | 0.97 | 0.88 | 0.92 | 148 |
| Identified | 0.68 | 0.90 | 0.78 | 42 |
| Accuracy | - | - | 0.88 | 190 |
| Insertion Model | Both Identified | Both Not Identified | Disagreement | Total |
|---|---|---|---|---|
| Gemini 2.5 Pro | 41 | 86 | 18 | |
| GPT 5 | 22 | 104 | 14 |
| Gemini 2.5 Pro | |||||
|---|---|---|---|---|---|
| Error Type | Valid Errors | Easy Prompt | Hallucination | Internal ID | Benchmark |
| Error in Assumptions | 1906 (99.7%) | 1659 (87.0%) | 1476 (89.0%) | 831 (56.3%) | 257 (30.9%) |
| Error in Algorithm/Proof | 1349 (99.3%) | 1122 (83.2%) | 960 (85.6%) | 378 (39.4%) | 106 (28.0%) |
| Incorrect or Incomplete Analysis | 512 (100.0%) | 383 (74.8%) | 353 (92.2%) | 235 (66.6%) | 54 (23.0%) |
| Error in Implementation | 200 (100.0%) | 179 (89.5%) | 157 (87.7%) | 105 (66.9%) | 26 (24.8%) |
| Inconsistencies in Definitions | 23 (95.8%) | 17 (73.9%) | 15 (88.2%) | 10 (66.7%) | 5 (50.0%) |
| GPT 5 | |||||
|---|---|---|---|---|---|
| Error Type | Valid Errors | Easy Prompt | Hallucination | Internal ID | Benchmark |
| Error in Assumptions | 3137 (99.4%) | 779 (24.8%) | 614 (78.8%) | 229 (37.3%) | 104 (45.4%) |
| Error in Algorithm/Proof | 2318 (99.5%) | 593 (25.6%) | 459(77.4%) | 214 (46.6%) | 75 (35.0%) |
| Incorrect or Incomplete Analysis | 1110 (99.7%) | 171 (15.4%) | 139 (81.3%) | 92 (66.2%) | 43 (46.7%) |
| Error in Implementation | 2186 (99.6%) | 96 (4.4%) | 74 (77.1%) | 45 (60.8%) | 16 (35.6%) |
| Inconsistencies in Definitions | 76 (98.7%) | 21 (27.6%) | 16 (76.2%) | 13 (81.2%) | 5 (38.5%) |
| Identification Model | 95% CI | Rank | |
|---|---|---|---|
| GPT 5 | 1.68 | [1.19, 2.31] | 1 |
| DeepSeek Reasoner v3.1 | 1.67 | [1.32, 2.22] | 2 |
| Grok 4 | 1.30 | [0.92, 1.89] | 4 |
| Claude Sonnet 4.5 | 1.32 | [1.10, 1.57] | 3 |
| Gemini 2.5 Pro | 1.18 | [0.27, 1.91] | 5 |
| Identification Model | 95% CI | Rank | |
|---|---|---|---|
| GPT 5 | 2.17 | [1.81, 2.68] | 1 |
| DeepSeek Reasoner v3.1 | 1.42 | [1.03, 1.65] | 3 |
| Grok 4 | 1.51 | [1.14, 1.91] | 2 |
| Claude Sonnet 4.5 | 1.23 | [1.13, 1.44] | 4 |
| Gemini 2.5 Pro | 1.03 | [0.27, 1.65] | 5 |
| Identification Model | 95% CI | Rank | |
|---|---|---|---|
| GPT 5 | 6.59 | [3.13, 9.77] | 1 |
| DeepSeek Reasoner v3.1 | 5.58 | [3.74, 7.33] | 2 |
| Grok 4 | 4.77 | [2.72, 6.48] | 3 |
| Claude Sonnet 4.5 | 4.29 | [2.90, 5.61] | 5 |
| Gemini 2.5 Pro | 4.68 | [2.93, 6.97] | 4 |
| Gemini 2.5 Pro | |||||
|---|---|---|---|---|---|
| Category | Valid Errors | Easy Prompt | Hallucination | Internal ID | Benchmark |
| Methods | 1702 (99.3%) | 1447 (85.0%) | 1273 (88.0%) | 628 (49.3%) | 185 (29.5%) |
| Exp/Results | 664 (99.7%) | 531 (80.0%) | 469 (88.3%) | 311 (66.3%) | 82 (26.4%) |
| Exp/Results + Methods | 572 (99.8%) | 496 (86.7%) | 451 (90.9%) | 226 (50.1%) | 69 (30.5%) |
| Intro + Methods | 335 (100.0%) | 285 (85.1%) | 250 (87.7%) | 118 (47.2%) | 32 (27.1%) |
| Exp/Results + Intro | 134 (100.0%) | 112 (83.6%) | 104 (92.9%) | 54 (51.9%) | 11 (20.4%) |
| GPT 5 | |||||
|---|---|---|---|---|---|
| Category | Valid Errors | Easy Filter | Hallucination | Internal ID | Benchmark |
| Methods | 2643 (99.4%) | 690 (26.1%) | 541 (78.4%) | 238 (44.0%) | 92 (38.7%) |
| Exp/Results | 2426 (99.5%) | 328 (13.5%) | 257 (78.4%) | 157 (61.1%) | 74 (47.1%) |
| Exp/Results + Methods | 2270 (99.5%) | 367 (16.2%) | 296 (80.7%) | 128 (43.2%) | 53 (41.4%) |
| Intro + Methods | 382 (99.5%) | 73 (19.1%) | 58 (79.5%) | 21 (36.2%) | 7 (33.3%) |
| Exp/Results + Intro | 199 (99.0%) | 35 (17.6%) | 26 (74.3%) | 17 (65.4%) | 10 (58.8%) |
| Insertion Model | Gemini 2.5 Pro | GPT 5 | ||
|---|---|---|---|---|
| # Papers | # Errors | # Papers | # Errors | |
| Claim Extraction | 100 | 742 | 100 | 1735 |
| Error Generation | 100 (100%) | 742 | 99 (99%) | 1735 |
| Filtering Invalid Errors | 100 (100%) | 741 (100%) | 99 (100%) | 1726 (99%) |
| Filtering Easy Errors Stage 1, Easy Error Prompt Filter | 100 (100%) | 604 (81%) | 84 (85%) | 299 (17%) |
| Filtering Easy Errors Stage 2, Internal Identification Filter | 98 (98%) | 385 (52%) | 69 (70%) | 163 (9%) |
| Identification Model | Accuracy @k=3 | Accuracy @k=10 |
|---|---|---|
| GPT 5 | 17.9% | 46.3% |
| DeepSeek Reasoner v3.1 | 23.5% | 27.8% |
| Grok 4 | 19.1% | 27.0% |
| Claude Sonnet 4.5 | 14.8% | 21.7% |
| Gemini 2.5 Pro | 12.5% | 14.6% |
Language Model Error Detection
Language model error detection identifies unreliable answers, reasoning steps, and actions so systems can flag, verify, or repair them.
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