Forecasts need a timeline and a carefully worded result state.The wording of matters greatly because hedging words like ‘might’, ‘may’, ‘likely’ can mean very different things to different people.
Calibration
Calibration is how well a forecast matches the actual occurrence of an event. An under-confident prediction will predict an event happen less frequently than it actually does vs. an over confident prediction which will predict that an event will happen more frequently than it does.
Resolution
Resolution is how often a decisive prediction is made that an event occurs or does not occur. When predictions are only made around the fifty/fifty mark, these are cautious estimates. When estimates are further in the binary (this will occur, this will not occur), these are decisive estimates.
Brier Score
A measurement of the distance between a forecast and what happened. Note that a brier score can be relative to the difficulty of the task. For example, in cases of stability or rare events, a simple algorithm like predict-no-change (or always predict the stable value) will do quite well. You need to benchmark against other forecasters.
0 is perfect. .5 is a hedged 50/50 call or random guessing 2 being perfectly wrong (every time something happens, it is predicted it won’t and vice versa)