As for lexical errors, a number of existing taxonomies further distinguish among translation errors due to missing words, extra words, or incorrect lexical choice.
given the proven difficulty of disambiguating between these three subclasses (Popović and Ney, 2011;Fishel et al., 2012), we prefer to rely on a more coarse-grained linguistic error classification where lexical errors include all of them (Farrús Cabeceran et al., 2010).