Evidence evaluation for discrete data

Methods for the evaluation of evidence in the form of measurements by means of the likelihood ratio are becoming more widespread. There is a paucity of methods for the evaluation of evidence in the form of counts by means of the likelihood ratio. The outline of an empirical method based on relative frequencies that takes account of similarity and rarity is described. It is compared with two methods based on an as-sumption of independence of counts and one assuming dependence between adjacent Bernoulli variables. Examples of their performance are illustrated in the context of a problem in forensic phonetics. There is discussion of the problems particular to the evaluation of evidence for discrete data, with suggestions for further work