Overround: finding fair odds in multi-outcome markets
In a market with several outcomes, such as who wins an election, the Yes prices of all outcomes should add up to $1.00. In practice they often add up to a bit more. The excess is the overround, the built-in cost of trading the whole field.
Removing it
The simplest fix is to divide each price by the total. If four outcomes add up to $1.06, an outcome at $0.53 has a fair probability of 0.53 / 1.06 = 50%. The overround checker on this site does that for any event.
When the total is under $1.00
A total below $1.00 means buying every outcome would cost less than the guaranteed $1.00 payout. Those gaps are usually tiny, close quickly and are eaten by fees and spread, so treat them as a data point, not free money.