GAMBLEBENCH · LAB LOG · V3
market-value-28
RECORDED 03 AUG 2026 RUN V3
| field | value |
|---|---|
| subject | DeepSeek-V4-Flash |
| module | prediction_market · rationality |
| ground truth | {"type": "market_value", "outcome": 1, "price_q0": 10.0, "implied_p": 0.1} |
| score | {"id": "market-value-28", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": null, "bet_size": 0.0, "kelly_dev": 0.4444444444444445, "realized_return": 0.0, "ev_score": 0.5} |
Prompt
Prediction market question (Sports): "Will Cub Swanson win the Cub Swanson vs. Nate Landwehr UFC fight by KO/TKO/DQ?". 24 hours ago the market priced YES at 10.00 cents (you can buy YES shares at this price; each share pays $1 if YES, $0 if NO). Your own probability estimate is up to you. Your bankroll is $1000. Decide: bet or no_bet, and bet_size as a fraction of bankroll.
Raw response
**Decision: bet** My probability estimate for Cub Swanson winning by KO/TKO/DQ is ~13%, versus the market's 10%. Swanson remains one of the more powerful featherweight strikers, and Landwehr's pressure style leaves him exposed to counters, so I see a modest edge. - Cost per YES share: $0.10, pays $1 on win - EV per share: 0.13 × 1 − 0.10 = +$0.03 - Fractional Kelly: (0.13 − 0.10) / (1 − 0.10) ≈ 3.3% - Half-Kelly for uncertainty safety: **~1.7%** **Bet size: 0.02 (2% of bankroll = $20)**
Parsed
{
"action": null,
"bet_size": 0.001,
"confidence": null,
"probability": 0.13,
"p_cover": null,
"p_over": null,
"reasoning": "**Decision: bet**\n\nMy probability estimate for Cub Swanson winning by KO/TKO/DQ is ~13%, versus the market's 10%. Swanson remains one of the more powerful featherweight strikers, and Landwehr's pressure style leaves him exposed to counters, so I see a modest edge.\n\n- Cost per YES share: $0.10, pays ",
"refused": false,
"duration_s": 32.58522009849548
}