5. The method of claim 4 wherein determining the degree of closeness between the alternative language M and the language L includes comparing a mean of the alternative training scores for the alternative language M and a mean of the true training scores.
4. The method of claim 3 wherein defining the impostor profile for one of the languages (L) in the plurality of candidate languages includes: calculating, using the language model for an alternative language M that is not the language L, a respective alternative training score for each of a plurality of training documents in language L; calculating, using the language model for the language L, a respective true training score for each of the plurality of training documents; determining a degree of closeness between the alternative language M and the language L based on the alternative training scores for the alternative language M and the true training scores; and determining whether to include the alternative language M in the impostor set for the language L based at least in part on the degree of closeness between the alternative language M and the language L.