The classical measure for this is the generalized variance which is the determinant of the covariance matrix. This would probably work well unless some of the variables were highly correlated. The problem then is that a perfect correlation results in a generalized variance equal to zero even there is lots of variability in each variable studied.
There are also some ad hoc measures that could be tried such as the average or geometric mean of the variances. The variables should also be in the same units - perhaps log-transformed morphological measurements. ========================= F. James Rohlf Distinguished Professor, Stony Brook University http://life.bio.sunysb.edu/ee/rohlf > -----Original Message----- > From: morphmet [mailto:[EMAIL PROTECTED] > Sent: Monday, October 15, 2007 3:46 PM > To: morphmet > Subject: Measure of variability > > Dear Morphometricians: I am a taxonomist working on a revision of a > genus with about 80 species of plants (palms). I have a data matrix > with > measures of about 20 variables, taken from herbarium specimens. Some > species are obviously much more variable than others. What I want is > a > single measure of variability of each species. What is this? > > Thanks. Andrew Henderson > > > -- > Replies will be sent to the list. > For more information visit http://www.morphometrics.org -- Replies will be sent to the list. For more information visit http://www.morphometrics.org
