Some preliminary definitions and the concept of probability

Before defining what probability is, some preliminary definitions are required. The first thing to point out is that an experiment is characterised by the fact that there are different potential outcomes and it is not possible to predict the specific outcome that is going to occur. For example, if a die is rolled, it is not possible to predict which of the six digits will face upward. Similarly, if an experiment involves measuring the intelligence quotient, then it is not possible to predict the actual score that a randomly sampled person will obtain.