b2: B2 metric

In treestats: Phylogenetic Tree Statistics

B2 metric

Description

Balance metric that uses the Shannon-Wiener statistic of information content. The b2 measure is given by the sum over the depths of all tips, divided by 2^{d}, e.g. \sum d_i / 2^{d_i}

Usage

b2(phy, normalization = "none")

Arguments

phy	phylo object or ltable
normalization	"none" or "yule", when "yule" is chosen, the statistic is divided by the Yule expectation, following from theorem 3.7 in Bienvenu 2020.

Value

b2 statistic

References

K.-T. Shao and R. R. Sokal. Tree Balance. Systematic Zoology, 39(3):266, 1990. doi: 10.2307/2992186.

Bienvenu, François, Gabriel Cardona, and Celine Scornavacca. "Revisiting Shao and Sokal’s $$ B_2 $$ B 2 index of phylogenetic balance." Journal of Mathematical Biology 83.5 (2021): 1-43.

treestats documentation built on Aug. 24, 2026, 5:09 p.m.