Relative frequency

“a” be number of times event A has occurred among the n reptitions, a / n is relative frequency.

\(f_{A} = \frac{n_{A}}{n}\)

\(f_{A}\) = 1 iff A occurs every time among n repetitions.

\(f_{A}\) = 0 iff A does not occur at all.

As experiment is repeated more times, \(f_{A}\) stabilizes.