Back to feed
Dev.to
Dev.to
6/16/2026
When Polymarket says 70%, does it happen 70% of the time? I checked against 19.4M price snapshots.

When Polymarket says 70%, does it happen 70% of the time? I checked against 19.4M price snapshots.

Short summary

Author analyzed 19.4M Polymarket price snapshots spanning 80 days to measure market calibration using reliability diagrams—whether events priced at 70% resolve 70% of the time. Results reveal the favorite-longshot bias: longshots systematically overpriced, favorites underpriced. Free API and complete Python methodology shared; author discusses selection bias and liquidity limitations.

  • •Built 80-day archive of 19.4M Polymarket price snapshots with ground-truth resolution labels
  • •Reliability diagrams show prediction markets exhibit classic favorite-longshot bias
  • •Free API and open-source methodology; includes Python code and discussion of statistical caveats

Generated with AI, which can make mistakes.

#research-breakthrough#market-trend#open-source
Read full article at Dev.to

Is this a good recommendation for you?

Explore more

17 million Polymarket price snapshots, collected on one Mac for $0/month
Dev.to
Building a Polymarket Trading Bot: Architecture, Execution, and Risk Management
Dev.to
Building a Production Polymarket Trading Bot: Lessons from 4 Strategies
Dev.to
The exact math that made $40,000,000 out of Polymarket (Full roadmap)
Dev.to