Same headline, different contract: a repeatable research study

The research question

When two venues cover the same event, do their contracts actually resolve on the same evidence? Start with a documented rule comparison. Only an equivalent pair can proceed to a measured price-difference study.

A reproducible protocol

Record stable event and contract IDs, exact outcome labels, threshold and timeframe, resolution source, cancellation terms, and the reviewed decision. Publish the source references and the reason for each inclusion or exclusion.

For an approved equivalent pair, retain contemporaneous quotes for the same side and size. Total purchase price equals executable ask multiplied by quantity plus applicable fees. Compare totals only when spread and sufficient depth are known. A missing input invalidates the lowest-price claim.

• Define the sample and observation window before collecting results.
• Keep separate currency units and volume windows.
• Publish missing observations and exclusions alongside results.
• Report named venues and capture times, not a universal market claim.

Pilot: 2026 US Congress control

The Kalshi CONTROL rules use the Speaker’s party for House control and the President Pro Tempore’s party for Senate control, with specified provisions for accelerated determination. The related Polymarket international rules start with voting-seat majorities and a Senate tie-break condition.

These definitions are materially different. The source comparison treats them as related, not equivalent. No cross-venue price difference, lowest-price result, or executable opportunity is asserted. Read the candidate event page for the exact source references.

What the study can establish

This study compares contract definitions. It does not measure a historical price difference. A numerical follow-up needs equivalent contracts, a defined sampling window and contemporaneous observations with reuse rights. Without those inputs, no average difference or historical performance result can be calculated.

Sources and citation

1. Kalshi CONTROL rules
2. Kalshi combination rules
3. Polymarket international: 2026 balance of power

PlayPicks analysis is original synthesis. Linked provider documents remain the primary source for their own contract terms.