Even when larger units are explicitly represented in DSMs (McCarthy et al., 2003;Reddy et al., 2011;Mikolov et al., 2013c;Ferret, 2014), it is not clear whether the quality of these representations is comparable to the representations of single words.
when building vectors for larger units, their generally lower frequencies in corpora (Kim and Baldwin, 2006) may combine with morphosyntactic phenomena to increase sparsity even further, often requiring non-trivial preprocessing (lemmatization and word reordering) to conflate variants.