Perhaps there’s some back story to this post that I missed, so forgive me if what I’m about to say has been discussed.
You might consider reading “Superforecasting: The Art and Science of Prediction,” by Philip Tetlock. Or go to the Good Judgment Project web site and watch the 5-part Superforecasting master class.
First, the question has to pass the clairvoyant test. Second, you might want to have some scheme for Bayesian updating your forecast. And then you’ll want to use Brier Scores (or something like them) to assess your accuracy.
If you know R, there’s actually a Brier score function you can use. But I can’t imagine it’s very difficult to set up in Excel.
Again, sorry if I’m stating the obvious.
Donald Rumsfeld famously identified known knowns, known unknowns, and unknown unknowns. Most people I knew assumed there were no unknown knowns. But I worked as a Knowledge Manager for about five years, and came to believe that unknown knowns — mainly in the form of institutional and tacit knowledge — contained the real gold. I think this is directly relatable to this concept of “intellectual dark matter.