How to read an expected value
Expected value is the average result of a trade if you could repeat it many times. Buy Yes at $0.40 while believing the true chance is 55%, and each share is worth about $0.15 more than you paid.
The number only exists relative to your own probability estimate. EV is not a market property; it is the distance between the price and your view, and it is negative for whoever is on the other side if you are right.
Where the probability estimate comes from
A positive EV calculation is only as good as the probability that goes into it. If that probability is a guess, so is the EV, however precise it looks.
This is why traders check their calibration over time: not whether individual calls were right, but whether the things they called 70% happened about 70% of the time. The Brier score measures that directly.
Where 0xinsider uses expected value
Expectancy, the realized counterpart of EV, runs on trader profiles as a rolling series over 7-day and 30-day windows. It shows whether a trader's average outcome per trade has stayed positive as the sample grew, which is the check that separates edge from a good month.
