Table 3.
List of measures with n being the number of observations, d the total number of dimensions, k any specific row in the matrix, Centroid being their mean and σ 2 their variance. Γ is the Gamma distribution and λi the eigenvalue of each dimension and qi and pi are any pairs of coordinates
Name | Definition | Captures | Source | Notes | |
---|---|---|---|---|---|
Average Euclidean distance from centroid |
|
Size | Laliberté and Legendre (2010) | The functional dispersion (FDis – without abundance) | |
Sum of variances |
|
Size | Foote (1992) | Common measure used in palaeobiology (Ciampaglio et al., 2001; Wills, 2001) | |
Sum of ranges |
|
Size | Foote (1992) | More sensitive to outliers than the sum of variances | |
Ellipsoid volume |
|
Size | Donohue et al. (2013) | Less sensitive to outliers than the convex hull hypervolume (Blonder, 2018; Díaz et al., 2016) | |
Minimum spanning tree average distance |
|
Density | Sedgewick (1990) | Similar to the unscaled functional evenness (Villéger et al., 2008) | |
Minimum spanning tree distances evenness |
|
Density | Villéger et al. (2008) | The functional evenness without weighted abundance (FEve; Villéger et al., 2008) | |
Average nearest neighbor distance |
|
Density | Foote (1992) | The density of pairs of observations | |
Average displacement |
|
Position | This paper | The ratio between the observations' position from their centroid and the center of the trait space (coordinates: 0, 0, 0,…). A value of 1 indicates that the observations' centroid is the center of the trait space |