6 posts
Prediction markets are accurate where they are deep and short dated, and unreliable where they are not. On a cross platform sample of resolved markets measured to 14 October 2025, Polymarket scored a Brier loss of 0.1652 and Kalshi 0.1982, against 0.25 for always guessing 50 percent. On the 2024 US election specifically, one study found that only 67 percent of Polymarket markets priced the eventual winner above 50 percent.
6 min read
A Brier score measures how far your probabilities were from reality. For each forecast, take the probability you gave, subtract the outcome written as 1 for happened and 0 for did not, and square the result. Average that over all your forecasts. Zero is perfect, 0.25 is what you get by saying 50 percent every time, and 1 is as wrong as it is possible to be.
8 min read
Calibration is the match between what you claim and what happens. If you are calibrated, the events you call 70 percent happen about 70 percent of the time, the ones you call 90 percent happen about 90 percent of the time, and so on down the scale. It is a property of a batch of forecasts, never of one. A single 70 percent call that comes true proves nothing.
7 min read
Forty terms used in prediction markets and forecasting, each defined in one sentence with one example. The terms are grouped by where you meet them: market mechanics, probability and scoring, resolution, platforms, and the words insiderz uses. Nothing here assumes you have traded anything.
11 min read
A superforecaster is someone who ranked in the top 2 percent for accuracy across hundreds of scored questions and then kept doing it. The label came out of a research tournament, not a marketing department, and the advantage is measurable: better calibration, sharper separation of what happens from what does not, and a set of working habits that are cheap to copy. Nothing in the list requires talent you can only be born with.
9 min read
A 34 percent chance means that across a large set of claims made with the same confidence, about 34 out of every 100 come true. It is a statement about a group, not about one event. When the event happens, the 34 percent forecast was not wrong. It was a forecast that said this happens about a third of the time, and a third of the time is often.
5 min read
