W.E.T. Election Heat Index: methodology

The W.E.T. Election Heat Index is a daily 0–100 reading of how contested the elections prediction markets are — how many races are genuine toss-ups versus decided.

Components

Each day the index pulls active markets from the elections category (Kalshi + Polymarket). No keyword filter is applied — every priced election market is a component.

Value

Each race contributes once, through its leading market (the current favorite). Competitiveness of that market is 1 − 2 × |p − 0.5|, where p is the implied YES probability: a coin-flip (p = 0.5) scores 1.0, a decided front-runner (p near 1) scores 0. The index is the volume-weighted mean competitiveness across races, expressed 0–100 — a high reading means the board is full of close races. No single race may exceed 20% of the weight (excess redistributed), so one mega-market can't dominate the reading. With fewer than three races live, the index reports insufficient data.

Publication & freshness

Computed and published daily to a durable, dated snapshot; the "last moved" date advances only on a ≥0.5-point change, and every point is appended to a permanent history.

What this index is not

This is a benchmark reading of market prices, not a W.E.T. forecast and not advice. A high value does not predict that the event happens — it reports what prediction-market traders are collectively pricing right now. Prices move continuously and can be wrong.

An accuracy record for a benchmark requires resolved outcomes accumulated over time. W.E.T. publishes this index daily with a dated, immutable history from first publication — that published series is the audit trail. Calibration analysis will ship strictly when the resolved-outcome corpus supports it, never before. See the site methodology for the same discipline applied to the W.E.T. Score.