Average leaf depth statistic. The average leaf depth statistic is a normalized version of the Sackin index, normalized by the number of tips.

Average leaf depth statistic. The average leaf depth statistic is a normalized version of the Sackin index, normalized by the number of tips.

Usage

average_leaf_depth(phy, normalization = "none")

Arguments

phy

phylo object or ltable

normalization

"none" or "yule", in which case the statistic is divided by the expectation under the yule model, following Remark 1 in Coronado et al. 2020.

Value

average leaf depth statistic

References

M. Coronado, T., Mir, A., Rosselló, F. et al. On Sackin’s original proposal: the variance of the leaves’ depths as a phylogenetic balance index. BMC Bioinformatics 21, 154 (2020). https://doi.org/10.1186/s12859-020-3405-1 K.-T. Shao and R. R. Sokal. Tree balance. Systematic Zoology, 39(3):266, 1990. doi: 10.2307/2992186.

Examples

simulated_tree <- ape::rphylo(n = 10, birth = 1, death = 0)
average_leaf_depth(simulated_tree)
#> [1] 3.8