R = H₀ − H

EXAMPLE Let $\left\{a,b,c\right\}$ be a set of three events and let $p(a)=\mathrm{0,5}$, $p(b)=\mathrm{0,25}$ and $p(c)=\mathrm{0,25}$ be the probabilities of their occurrences. The redundancy of this set is: $R=\mathrm{1,585}\text{ Sh}-\mathrm{1,50}\text{ Sh }=\mathrm{0,085}\text{ Sh}$.

Note 1 to entry: Usually, messages can be represented with fewer characters by using suitable codes; the redundancy can be considered as a measure of the decrease of the average length of the messages accomplished by appropriate coding.