If a meteorologist says there is a 70% chance of rain and it doesn’t rain, is she wrong? Not necessarily. Implicitly, her forecast also says there is a 30% chance it will not rain. So if it doesn’t rain, her forecast may have been off, or she may have been exactly right. It’s not possible to judge with only that one forecast in hand. The only way to know for sure would be to rerun the day hundreds of times. If it rained in 70% of those reruns, and didn’t rain in 30%, she would be bang on. Of course we’re not omnipotent beings, so we can’t rerun the day—and we can’t judge.
