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Re: my lame cladistic questions



What are (in easy words):
[...]
- the tree length measured in steps?

Each change from a state to another is called a step. The total number of those is the length of the tree.


- consistency and retention indexes;

CI = (length of the tree)/(minimum number of steps that any conceivable tree could have).


RI = ((maximum number of steps that any conceivable tree could have) minus (tree length))/((maximum number of steps that any conceivable tree could have) minus (minimum number of steps that any conceivable tree could have)).

And while we are at it, the rescaled consistency index = RC = CI x RI.

All of these apply not only to entire trees, but also to individual characters.

- a jackknife frequency;

Jackknifing is a method of determining how robust a tree is. The more often a clade is found in this procedure, the higher its jackknife frequency = jackknife value = jackknife percentage...


- a Bremer support value;

How many more steps are required to destroy that clade. That is, if a tree with one more step lacks the clade in question, that clade had a Bremer value of 1.