The how and why of branch support and partitioned branch support, with a new index to assess partition incongruence

Abstract

An introduction and step-by-step guide to the calculation of branch support (BS) and partitioned branch support (PBS) is provided, along with a new summary measure of conflict among data partitions, the partition congruence index (PCI). Patterns of PCI vs. BS are compared for two data matrices from butterflies. PCI is a close mirror of BS unless BY is relatively low and there is a lot of conflict among data partitions, in which case PCI becomes negative. Some theoretical concerns relating to PBS are noted. © The Willi Hennig Society 2006.