Sensitivity of dispersion measures to distributional patterns and corpus design
Lukas Sönning, Jesse Egbert · International Journal of Corpus Linguistics · 2026
Abstract Recent work has shown that dispersion measures respond to multiple features in the data: Juilland’s D varies systematically with the number of corpus parts, and all commonly used indices are affected by the frequency of an item. This study uses a simulation approach to provide further insights into the sensitivity of dispersion measures to differences in corpus design (number of texts, average text length, distribution of text lengths) and distributional milieu (frequency and evenness of distribution). Our results suggest that, within the settings covered by our analysis, the factors frequency and evenness of distribution have roughly the same impact, though there is some variation among measures. The average text length emerges as another feature that leaves its mark on the observed scores. Finally, we note that D 2 exhibits the same weakness as D — it varies with the number of corpus parts that enter the analysis.