How Much Does Corpus Choice Change Dependency-Distance Estimates?
A study compared the average dependency distance estimates for 38 language-specific tree pairs in the Universal Dependency Treebank v2.18. The results showed that consistency across treebanks was extremely poor: replacing a treebank would reverse nearly 40% of language rankings, and treebank selection explained approximately 29% of the inter-group variance. This difference exceeded the sampling error within the treebanks and persisted under twelve preprocessing specifications. Although all treebanks confirmed minimal dependency length (normalized ratios below 1), the data supported the view that dependency distances are a composite of grammatical, genre, and annotation factors influenced by corpus conditions, rather than stable language-level parameters; the qualitative dependency length model remained valid after replacing the corpus, but cross-linguistic ordinal rankings no longer held.