Ensemble retention index
ensemble retention index (RI)
Glossary of "Cladistics (2nd ed.)" by Kitching et al. (1998)
- A measure of the amount of similarity in a data matrix that can be interpreted as synapomorphy on a given cladogram. The ensemble retention index is calculated is the ratio of (G - S) to (G - M), where G is the greatest number of steps that all characters can exhibit on any cladogram, M is the minimum number of steps all characters can exhibit on any cladogram and S is the minimum number of steps they can exhibit on the cladogram in question. See also retention index.
- Kitching, I. J., Forey, P. L. Humphries, C. J. & Williams, D. M. 1998. Cladistics, 2nd ed.: the Theory and Practice of Parsimony Analysis. -xii + 228 pp. Oxford University Press, New York.