Applied Quantitative Research & Open Data Suite
Reproducible studies and open data on binary prediction markets: a calibration study of 3,236 resolved Polymarket markets, the dataset behind it and the script that recomputes every number.
Calibration of Polymarket Prices: Brier Decomposition Across 3,236 Resolved Markets (2023–2026)
How well the Yes price 24 hours and 7 days before close matched outcomes, where longshots and mid-range favourites deviated, and how fees change the break-even probability.
Resolved Polymarket Markets 2023–2026
3,236 binary markets with volume of at least $50,000: question, close date, volume, Yes price 24 hours and 7 days before close, and outcome. Source: public Polymarket Gamma and CLOB APIs.
Venue Fee Schedules (Checked 22 Oct 2026)
Trading, redemption, deposit and withdrawal fees of Polymarket, Polymarket US, Kalshi, PredictIt, Betfair and Smarkets from their official pages, plus the measured margin of 1win Markets, with sources and dates.
Analysis Script (Python 3)
Reads the CSV and writes polymarket_calibration_results.json: Brier score, Murphy decomposition and calibration by price band, with and without multi-outcome events.
Calibration by Price Band (Preview)
Yes price 24 hours before close against the share of markets that resolved Yes, 3,236 resolved Polymarket markets (returns use only prices above 0.5¢):
| Price band | Markets | Mean price | Resolved Yes | Outcome − price, pp | Buy Yes return (95% CI) |
|---|---|---|---|---|---|
| 0–10¢ | 2,433 | 0.86% | 0.37% | −0.49 | −67.3% (−92.0…−42.6) |
| 10–20¢ | 106 | 14.32% | 11.32% | −3.00 | −24.2% (−65.1…+16.7) |
| 20–30¢ | 73 | 25.48% | 21.92% | −3.56 | −18.6% (−54.0…+16.9) |
| 30–40¢ | 39 | 34.15% | 23.08% | −11.07 | −29.8% (−70.1…+10.5) |
| 40–50¢ | 36 | 44.50% | 44.44% | −0.06 | −0.8% (−37.1…+35.5) |
| 50–60¢ | 41 | 55.22% | 73.17% | +17.95 | +32.4% (+7.7…+57.1) |
| 60–70¢ | 36 | 65.42% | 86.11% | +20.69 | +32.3% (+14.9…+49.8) |
| 70–80¢ | 59 | 75.11% | 86.44% | +11.33 | +14.8% (+3.1…+26.4) |
| 80–90¢ | 66 | 85.06% | 86.36% | +1.30 | +1.5% (−8.3…+11.3) |
| 90–100¢ | 347 | 98.01% | 98.56% | +0.55 | +0.6% (−0.7…+1.9) |
Open Science Standards & Academic Reproducibility
The dataset, the analysis script and its output are published in /papers/ together with a README that lists the columns and selection rules. The underlying prices and outcomes come from the public Polymarket APIs.
Download the CSV and polymarket_calibration_analysis.py from /papers/.
Run python polymarket_calibration_analysis.py; it writes polymarket_calibration_results.json next to the CSV.
Compare the output with the tables on the study page; every number there comes from this file.
Check the market terms
Partner link
1win Markets: check the quoted odds, embedded margin and settlement rules
Compare pricing and fees → Visit 1win Markets 18+ · Terms on site1win Markets uses bookmaker odds. It is not interchangeable with buying and selling exchange shares. Check the exact question, settlement rules, price and local availability before opening a position.
