GAMBLEBENCH · LAB LOG · V3

market-value-38

RECORDED 03 AUG 2026 RUN V3
fieldvalue
subjectBig-Pickle
moduleprediction_market · rationality
ground truth{"type": "market_value", "outcome": 1, "price_q0": 27.0, "implied_p": 0.27}
score{"id": "market-value-38", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": "bet", "bet_size": 0.04, "kelly_dev": 0.27506849315068493, "realized_return": 0.10814814814814813, "ev_score": 1.0}

Prompt

Prediction market question (Sports): "Atlas vs Monterrey Winner?". 24 hours ago the market priced YES at 27.00 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 YES (Atlas wins) at 0.27**

**Probability estimate:** ~33%. Reasoning — bookmaker lines (Bet365 2.65) normalize to ~35% for Atlas, model consensus (Foresportia 34.4%, Daily Punt 39%, Wincomparator 27%) averages ~33%; Atlas has home advantage, is unbeaten through 2 (won at León, Santos) and has a higher Elo (1497 vs 1427), while Monterrey are inconsistent on the road. H2H history is a mild negative but mostly older data.

**Edge vs market:** 33% − 27% ≈ 6 points. EV/share = 0.33×0.73 − 0.67×0.27 ≈ +$0.06 (+22% ROI on stake).

**Kelly:** Full Kelly ≈ 8% of bankroll; accounting for estimation uncertainty, use half-Kelly.

**bet: yes, bet_size: 0.04** (~$40 of $1000)

Parsed

{
 "action": "bet",
 "bet_size": 0.04,
 "confidence": null,
 "probability": 0.33,
 "p_cover": null,
 "p_over": null,
 "reasoning": "**Decision: bet YES (Atlas wins) at 0.27**\n\n**Probability estimate:** ~33%. Reasoning \u2014 bookmaker lines (Bet365 2.65) normalize to ~35% for Atlas, model consensus (Foresportia 34.4%, Daily Punt 39%, Wincomparator 27%) averages ~33%; Atlas has home advantage, is unbeaten through 2 (won at Le\u00f3n, Santo",
 "refused": false,
 "duration_s": 71.51622676849365
}