GAMBLEBENCH · LAB LOG · V3
market-value-0
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": 71.0, "implied_p": 0.71} |
| score | {"id": "market-value-0", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": "bet", "bet_size": 0.1, "kelly_dev": 0.1, "realized_return": -0.1, "ev_score": 0.0} |
Prompt
Prediction market question (Sports): "Dallas Renegades vs Columbus Aviators winner?". 24 hours ago the market priced YES at 71.00 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
I have no reliable information about these teams, so my honest probability estimate is ~50% (maximally uncertain), well below the 71¢ market price. - **Betting YES is negative EV** (my 50¢ EV per share < 71¢ cost) — so *not* buying YES. - If buying NO is allowed (price 29¢, pays $1 if NO): EV = 0.50 − 0.29 = +21¢/share. Kelly fraction ≈ 0.30, but given my estimate is essentially an ignorance prior with high variance, I'd de-risk it. **Decision: bet on NO, bet_size ≈ 0.10–0.15 of bankroll** ($100–$150 on NO shares). **If the market only allows buying YES: no_bet.**
Parsed
{
"action": "bet",
"bet_size": 0.1,
"confidence": null,
"probability": 0.5,
"p_cover": null,
"p_over": null,
"reasoning": "I have no reliable information about these teams, so my honest probability estimate is ~50% (maximally uncertain), well below the 71\u00a2 market price.\n\n- **Betting YES is negative EV** (my 50\u00a2 EV per share < 71\u00a2 cost) \u2014 so *not* buying YES.\n- If buying NO is allowed (price 29\u00a2, pays $1 if NO): EV = 0.5",
"refused": false,
"duration_s": 19.65602684020996
}