Dear morphometricians, some time ago you gave me helpful suggestions about how to compare shape trajectories between groups by computing the angle between the vectors (for instance, allometric trajectories of males and females). I would like to ask you some more questions about comparisons of angles. Thanks in advance for your help.
1) Is there any resampling statistics that allows to test for the significance of the angle between vectors of 2 (or more) groups using the shape variables obtained in the initial superimposition of the landmark configurations? I guess that if confidence intervals are computed using bootstraps, each time a bootstrap is performed a new superimposition has to be done, then new vectors are computed and the angle is calculated. Performing a new superimposition at each stage of the resampling procedure is what I'd like to avoid, but I am not sure whether there is any alternative to bootstraps for doing this. 2) Is it possible to compare the angle of two vectors obtained with separate regressions (or PLS etc.) of shape (same group) onto two different variables, or sets of variables (say, shape onto V1 vs shape onto V2)? 3) If 2) is possible, can the significance of the angle shape-V1/shape-V2 be tested by performing permutations of the order of specimens in (say) V1? Again, thanks. Cheers Andrea Dr. Andrea Cardini Hull York Medical School The University of York, Heslington, York YO10 5DD, UK & The University of Hull,Cottingham Road, Hull HU6 7RX, UK tel. 01904 321752 fax 01904 321696 E-mail: [EMAIL PROTECTED] http://www.york.ac.uk/res/fme/people/andrea.htm ------------------------------------------------------------------------- Visita http://domini.interfree.it, il sito di Interfree dove trovare soluzioni semplici e complete che soddisfano le tue esigenze in Internet, ecco due esempi di offerte: - Registrazione Dominio: un dominio con 1 MB di spazio disco + 2 caselle email a soli 18,59 euro - MioDominio: un dominio con 20 MB di spazio disco + 5 caselle email a soli 51,13 euro Vieni a trovarci! Lo Staff di Interfree ------------------------------------------------------------------------- -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
