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Education6 min readJuly 15, 2025

What Is an Edge Score in Prediction Markets? (Complete Guide)

The edge score explained — how it's calculated, what the numbers mean, and how to use it to make better trading decisions on Polymarket and Kalshi.

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In prediction markets, your edge is your statistical advantage over the current market price. An edge score quantifies this advantage into a single actionable number.

The Simple Definition

An edge score tells you: based on current live data, does one side of this market appear to be underpriced relative to the other?

Polyscout AI's edge score ranges from -100 to +100:

  • +50 to +100: Strong YES-side edge. The live data suggests YES may be underpriced.
  • +20 to +50: Moderate YES edge. Worth monitoring or cautiously entering.
  • -20 to +20: No clear edge. Market appears fairly priced.
  • -20 to -50: Moderate NO edge. NO side may be underpriced.
  • -50 to -100: Strong NO-side edge.

The 4 Signals That Make Up the Score

1. Price Divergence (40% weight)

If your screenshot shows YES at 65c but live Polymarket has YES at 72c, the market moved 7 points in your favor. This is positive price divergence.

2. Order Book Imbalance (30% weight)

The order book shows how many buyers vs sellers are waiting. If YES bids are 3x deeper than NO asks, buyers are more aggressive — a bullish signal.

3. 24h Momentum (20% weight)

If the price has been trending up over the last 24 hours, that momentum often continues short-term. Trend-following is a known edge in prediction markets.

4. Volume Trend (10% weight)

Above-average trading volume indicates increased conviction. Thin volume markets can reverse quickly.

How to Act on the Edge Score

A score above +30 or below -30 is generally worth examining. Always combine the edge score with your own fundamental knowledge of the event. The score identifies when to look harder, not what to decide.

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