Scaling the chord and Hellinger distances in the range [0,1]: An option to consider

Abstract

The chord and Hellinger distances are commonly used as measures of resemblance in ecological studies. Both distances are bound within the range [0,√2]. We propose to scale them within the range [0,1]. The scaling is mainly justified to report beta diversity values in the range [0,1] properly. Moreover, results for both unscaled distances in multivariate techniques such as cluster analysis or ordinations are not directly comparable with similar graphical displays obtained with indices bound in the range [0,1]. Although comparability and/or interpretability of values are compromised, the used of the unscaled Hellinger and chord distances do not void their validity in ecological studies. Nonetheless, we have found one exception when comparing clustering models using the Gower distance criterion.

Keywords

• Beta diversity
• Euclidean distance
• Methodological unification
• Multivariate methods
• Resemblance measures