1. A method comprising: performing by one or more computer processors: obtaining a translation of a message in a first language to a second language wherein the translation was submitted by a user; generating a part-of-speech (POS) n-gram representation of the translation comprising a plurality of POS n-grams of two or more different lengths, wherein generating the POS n-gram representation comprises associating a respective probability with each of the POS n-grams; and determining an accuracy of the translation based on a combination of the probabilities.