RandomnessAt a fundamental level, assume there is a sample space consisting of all possible events or outcomes: we can use it to describe our uncertainty around which event will occur.P(A∪B)≤1P(A \cup B) \le 1P(A∪B)≤1Probability theory NotionProbabilityRandom Variable Probability theory Usageschi SquareThe Goodhart's LawOptimal Stopping Point