Hello Adrià The number of parameters in the model is equal to the number of transitions that are estimated, or free to vary. For example, if you have 3 states: A, B, and C, the ARD model estimates 6 rates, from A to B and vice versa, from B to C and vice versa and from A to C and vice versa. For the example you give below, if I understood correctly that you only have two trait-states, then if you fix B->A to 0 then that transition is no longer free to vary (thus not estimated by the model) and you’d only have a single transition being estimated, A->B.
Cheers Alejandro _______________________________________________ Dr Alejandro Gonzalez Voyer Investigador Titular B Coordinación de Docencia y Formación de Recursos Humanos Instituto de Ecología Laboratorio de Conducta Animal Instituto de Ecología Circuito Exterior S/N Ciudad Universitaria Universidad Nacional Autónoma de México México, D.F. 04510 México Tel: +52 55 5622 9044 E-mail: alejandro.gonza...@iecologia.unam.mx Web Site: http://alejandrogonzalezvoyer.com <http://alejandrogonzalezvoyer.com/> > On 21 Apr 2021, at 5:57, Adrià Bellvert <abellver...@gmail.com> wrote: > > Dear all, > I have been working with simmaps with the usual models (ER, ARD and SYM) > and some of my own ones. > The problem that I have come to is that I have the model ER and my model > that is ER but with the transition state that goes from A -> B but couldn't > turn back from B -> A. ER has 1 single parameter, but how many parameters > has my model and why? I need this information in order to be able to > compare these models based on AIC and choose the one most supported by my > data. > > Thanks in advance for any help > Adrià > > -- > *Adrià Bellvert* > PhD student. > *Departament de Biologia Evolutiva, Ecologia i Ciències Ambientals.* > *University of Barcelona.* > > [[alternative HTML version deleted]] > > _______________________________________________ > R-sig-phylo mailing list - R-sig-phylo@r-project.org > https://stat.ethz.ch/mailman/listinfo/r-sig-phylo > Searchable archive at http://www.mail-archive.com/r-sig-phylo@r-project.org/ [[alternative HTML version deleted]] _______________________________________________ R-sig-phylo mailing list - R-sig-phylo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo Searchable archive at http://www.mail-archive.com/r-sig-phylo@r-project.org/
