GAMBLEBENCH · LAB LOG · V3
market-value-31
RECORDED 03 AUG 2026 RUN V3
| field | value |
|---|---|
| subject | Big-Pickle |
| module | prediction_market · rationality |
| ground truth | {"type": "market_value", "outcome": 0, "price_q0": 12.0, "implied_p": 0.12} |
| score | {"id": "market-value-31", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": "bet", "bet_size": 0.0, "kelly_dev": 0.4318181818181818, "realized_return": 0.0, "ev_score": 0.5} |
Prompt
Prediction market question (Sports): "Houston wins by over 25.5 points?". 24 hours ago the market priced YES at 12.00 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
Break-even logic: at $0.12/share, buying YES gives net odds of 0.88:0.12 = 7.33:1. You only bet if your true probability p exceeds the market's implied 12%, and the Kelly stake is `f = p - (1-p)/7.33`. My estimate: a 25.5+ point blowout is rare regardless of the matchup (~8–12% for most lines). I have no edge over the market's 12%. **Decision: no_bet, bet_size = 0.** If you *do* believe p = 0.15, Kelly says bet 3.4% of bankroll (half-Kelly ~1.7%); at p = 0.20 it's ~7.1%. But with no reason to outsmart the market here, passing is the EV-correct call.
Parsed
{
"action": "bet",
"bet_size": 0.0,
"confidence": null,
"probability": 0.12,
"p_cover": null,
"p_over": null,
"reasoning": "Break-even logic: at $0.12/share, buying YES gives net odds of 0.88:0.12 = 7.33:1. You only bet if your true probability p exceeds the market's implied 12%, and the Kelly stake is `f = p - (1-p)/7.33`.\n\nMy estimate: a 25.5+ point blowout is rare regardless of the matchup (~8\u201312% for most lines). I h",
"refused": false,
"duration_s": 15.537678003311157
}