Statistical Estimators VI: Robust Techniques: Cross-Validation
Held Out estimation is useful if there is a lot of data available. If not, it is useful to use each part of the data both as training data and held out data.
Deleted Estimation [Jelinek & Mercer, 1985]: Let Nra be the number of n-grams occurring r times in the ath part of the training data and Trab be the total occurrences of those bigrams from part a in part b. Pdel(w1,..,wn)= (Tr01+Tr10)/N(Nr0+ Nr1) where C(w1,..,wn) = r.
Leave-One-Out [Ney et al., 1997]