GAMBLEBENCH · LAB LOG · V3
market-value-22
RECORDED 03 AUG 2026 RUN V3
| field | value |
|---|---|
| subject | DeepSeek-V4-Flash |
| module | prediction_market · rationality |
| ground truth | {"type": "market_value", "outcome": 0, "price_q0": 22.0, "implied_p": 0.22} |
| score | {"id": "market-value-22", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": "bet", "bet_size": 0.25, "kelly_dev": 0.10897435897435898, "realized_return": -0.25, "ev_score": 0.0} |
Prompt
Prediction market question (Sports): "Palestino vs Deportes Limache Winner?". 24 hours ago the market priced YES at 22.00 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 Palestino to win (home, vs a newly-promoted Deportes Limache): ~60%. At a YES price of 22¢, each share has expected value ~60¢, so +EV ≈ 0.60 − 0.22 = +0.38 per share (≈170% edge on price). Kelly: with p=0.60 and net odds b=(1/0.22)−1≈3.55, full Kelly ≈ 0.49. Using half-Kelly for variance/sizing safety: - **bet_size: ~0.25 of bankroll** ($250) Even with a conservative estimate of p=0.45 this remains strongly +EV (EV per share +0.23), so the bet is robust to estimation error.
Parsed
{
"action": "bet",
"bet_size": 0.25,
"confidence": null,
"probability": 0.6,
"p_cover": null,
"p_over": null,
"reasoning": "**Decision: bet**\n\nMy probability estimate for Palestino to win (home, vs a newly-promoted Deportes Limache): ~60%. At a YES price of 22\u00a2, each share has expected value ~60\u00a2, so +EV \u2248 0.60 \u2212 0.22 = +0.38 per share (\u2248170% edge on price).\n\nKelly: with p=0.60 and net odds b=(1/0.22)\u22121\u22483.55, full Kelly ",
"refused": false,
"duration_s": 14.53067398071289
}