risk or uncertainty

known unkowns and unkown unkowns.

Or, risk describes the "spread" of a known probability distribution - for example, the chance that you'll roll something other than a 7 given that you know you're throwing two six-sided dice. Uncertainty emerges when you don't even know whether the dice have six sides, so you are forced to entjavascript:void(0)ertain the possibility that your entire model of the world is incorrect.

Quote from Hussman

His approach is to use an ensemble model, which gives a measure of the uncertainty