Proportional Change and Patterns of Homoplasy: Sanderson and Donoghue Revisited.

The effects of two parameters, (1) the number of taxa and (2) the percentage of characters that change per node (referred to as the amount of proportional change or APC) on the retention index (RI) and the consistency index (CI) were examined. Random data sets were generated with a variety of different combinations of the number of taxa and the APC; five replicates for each unique combination were generated producing a total of 660 data sets. Results suggest that both the number of taxa and the APC are significantly correlated with the CI.