For every true boundary in a document, RS predicts a boundary drawn from a normally distributed set around the true boundary with scalable standard deviation σ.
smaller values for σ result in better segmentations because the probability of selecting the true boundary increases, e.g., for σ = 2, more than 68% of all predicted boundaries are at most 2 sentences away from the true boundary and more than 99% of all predicted boundaries are located within a range of 6 sentences from it.