# The Multivac — Evaluation Report

**Evaluation ID:** EVAL-20260402-113127
**Date:** Jan 14, 2026
**Category:** reasoning
**Question ID:** REASON-001

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## Question

You're given two sealed envelopes. You're told one contains twice as much money as the other, but you don't know which is which.

You pick envelope A and find $100.

You reason: "Envelope B either has $50 or $200. If I switch, I have a 50% chance of getting $50 and 50% chance of getting $200. Expected value of switching = 0.5($50) + 0.5($200) = $125. That's more than $100, so I should switch."

But wait - this logic would apply no matter what amount you found. That can't be right.

What's the flaw in this reasoning? Provide a rigorous explanation.

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## Winner

**GPT-5.4** (openrouter)
- Winner Score: 9.54
- Matrix Average: 8.16
- Total Judgments: 80

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## Rankings

| Rank | Model | Provider | Avg Score | Judgments |
|------|-------|----------|-----------|----------|
| 1 | GPT-5.4 | openrouter | 9.54 | 9 |
| 2 | Claude Opus 4.6 | openrouter | 9.19 | 8 |
| 3 | Claude Sonnet 4.6 | openrouter | 9.13 | 9 |
| 4 | MiMo-V2-Flash | Xiaomi | 8.82 | 9 |
| 5 | Grok 4.20 | openrouter | 8.78 | 9 |
| 6 | Gemini 2.5 Flash | openrouter | 8.41 | 9 |
| 7 | DeepSeek V4 | openrouter | 7.74 | 9 |
| 8 | GPT-OSS-120B | OpenAI | 6.81 | 9 |
| 9 | Gemini 3.1 Pro | openrouter | 5.03 | 9 |

---

## 10×10 Judgment Matrix

Rows = Judge, Columns = Respondent. Self-judgments excluded (—).

| Judge ↓ / Resp → | Gemini 3.1 Pro | DeepSeek V4 | Claude Opus | GPT-5.4 | Grok 4.20 | Claude Sonnet | MiMo-V2-Flash | GPT-OSS-120B | Gemini 2.5 | MiniMax M2.5 |
|---|---|---|---|---|---|---|---|---|---|---|
| Gemini 3.1 Pro | — | 5.3 | 10.0 | 10.0 | 8.5 | 10.0 | 8.6 | 3.2 | 9.4 | · |
| DeepSeek V4 | 8.3 | — | 8.9 | 9.7 | 9.7 | 9.7 | 9.7 | 9.7 | 9.7 | · |
| Claude Opus | 3.1 | 6.2 | — | 9.4 | 8.2 | 9.2 | 8.2 | 4.5 | 6.8 | · |
| GPT-5.4 | 2.0 | 8.0 | 8.2 | — | 8.7 | 8.4 | 8.0 | 5.2 | 8.3 | · |
| Grok 4.20 | 6.2 | 8.4 | 8.8 | 8.8 | — | 8.8 | 8.7 | 7.8 | 7.8 | · |
| Claude Sonnet | 4.3 | 7.2 | 10.0 | 9.7 | 8.8 | — | 8.4 | 5.6 | 8.4 | · |
| MiMo-V2-Flash | 4.8 | 9.0 | 9.2 | 9.7 | 8.7 | 9.2 | — | 8.7 | 8.8 | · |
| GPT-OSS-120B | 5.5 | 8.4 | · | 9.3 | 8.0 | 8.4 | 9.3 | — | 8.3 | · |
| Gemini 2.5 | 7.3 | 8.8 | 9.1 | 9.8 | 9.3 | 9.1 | 9.7 | 9.4 | — | · |
| MiniMax M2.5 | 3.8 | 8.4 | 9.3 | 9.6 | 9.3 | 9.3 | 9.0 | 7.2 | 8.2 | — |

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## Methodology

- **10×10 Blind Peer Matrix:** All models answer the same question, then all models judge all responses.
- **5 Criteria:** Correctness, completeness, clarity, depth, usefulness (each scored 1–10).
- **Self-judgments excluded:** Models do not judge their own responses.
- **Weighted Score:** Composite of all 5 criteria.

---

## Citation

The Multivac (2026). Blind Peer Evaluation: REASON-001. app.themultivac.com

## License

Open data. Free to use, share, and build upon. Please cite The Multivac when using this data.

Download raw JSON: https://app.themultivac.com/api/evaluations/EVAL-20260402-113127/results
Full dataset: https://app.themultivac.com/dashboard/export