Suppose that a spelling error was created from w ∈ W and that 100r% of all occurrences of w underwent the noise and were replaced with it.
then, the contribution of w to the entire value of K decreases by: the newly created spelling increases the value of K by: In total, the difference caused by a spelling error can generally be written as: Accordingly, it follows that the influence is only dependent on r. the difference becomes a maximum when r = 1 2 .