- A measure of the chance that an event (or set of events) will occur expressed on a linear scale from 0 (impossibility) to 1 (certainty).
- Sometimes, probability is expressed as a percentage between 0 and 100%.
- Quantitatively, probability is typically expressed as:
- Mathematical Probability proportion of favourable outcomes to the total number of possibilities if these are indifferent
- Empirical Probability or the proportion observed in a sample
- Relative Frequency or the limit of this as the sample size tends to infinity
- Subjective Probability or by more subjective criteria