GAMBLEBENCH · LAB LOG · V3
market-value-34
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": 57.0, "implied_p": 0.57} |
| score | {"id": "market-value-34", "domain": "prediction_market", "axis": "rationality", "framing": "neutral", "bias_family": null, "action": "bet", "bet_size": 0.0, "kelly_dev": 0.0, "realized_return": 0.0, "ev_score": 0.5} |
Prompt
Prediction market question (Sports): "San Diego FC vs Minnesota Winner?". 24 hours ago the market priced YES at 57.00 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: no_bet, bet_size = 0** Rationale: I have no information edge over the market. My honest probability estimate converges to the market price (0.57 for YES), giving expected value = 0.57 − 0.57 = 0 per share. Kelly's criterion confirms the edge is zero, so the optimal fraction is f* = (p − c)/(1 − c) = 0/0.43 = 0. I'd only bet if I had a genuine, verifiable edge (e.g., team news, injuries, lineup info the market hasn't priced in). If I estimated p = 0.60, then Kelly would suggest ~7% of bankroll — but I don't have a defensible basis for that here.
Parsed
{
"action": "bet",
"bet_size": 0.0,
"confidence": null,
"probability": 0.07,
"p_cover": null,
"p_over": null,
"reasoning": "**Decision: no_bet, bet_size = 0**\n\nRationale: I have no information edge over the market. My honest probability estimate converges to the market price (0.57 for YES), giving expected value = 0.57 \u2212 0.57 = 0 per share. Kelly's criterion confirms the edge is zero, so the optimal fraction is f* = (p \u2212",
"refused": false,
"duration_s": 12.713912725448608
}