Dependency-distance estimates derived from a single corpus are routinely treated as properties of a language, yet this assumption has not been tested across independently compiled corpora.
We compared mean dependency-distance estimates across 38 same-language treebank pairs from Universal Dependencies v2.18, using concordance correlation, Bland-Altman analysis, and a twelve-specification multiverse design.
Cross-treebank agreement was moderate at best: substituting one treebank for another reversed nearly 40 percent of pairwise language orderings, and treebank choice accounted for roughly 29 percent of between-group variance.
This disagreement substantially exceeded within-treebank sampling error and persisted across all twelve preprocessing specifications.
Nevertheless, every treebank confirmed dependency-length minimization (normalized ratio below 1).
The data are more consistent with MDD as a corpus-conditioned composite of grammatical, register, and annotation factors than as a stable language-level parameter:
the qualitative DLM universal survives corpus substitution, but the ordinal cross-linguistic ranking does not.