Mike, does this mean that, in general, the
position of the semilandmarks is strongly sample
dependent, which would mean that also the shape
distances might change remarkably despite the
fact one has the same number of points on exactly the same surface?
Say that I have two samples, A and B. I first (1)
superimpose (and slide) within A. Then I do the
same with both A and B together (2). Could I get
appreciable differences between A1 and A2 just because of the sliding?
All Procrustes shape distances depend on the
sample composition. However, in my experience,
differences between A1 and A2 tend to be
negligible with 'standard' landmarks. Is this
different with semilandmarks? Are there
sensitivity analyses that explore the issue (if it's an issue)?
Thanks in advance.
Cheers
Andrea
At 17:06 18/02/2016, Collyer, Michael wrote:
Contrary to your logic, subsetting your sample
could have an effect. Your mean configuration
would change in each of the subsamples, from the
mean of your original sample, thus changing the
reference configuration used in the separate
GPAs performed. The reference configuration has
a prominent role in the sliding of landmarks.
Dr. Andrea Cardini
Researcher, Dipartimento di Scienze Chimiche e
Geologiche, Università di Modena e Reggio Emilia,
Via Campi, 103 - 41125 Modena - Italy
tel. 0039 059 2058472
Adjunct Associate Professor, Centre for Forensic
Science , The University of Western Australia, 35
Stirling Highway, Crawley WA 6009, Australia
E-mail address: alcard...@gmail.com, andrea.card...@unimore.it
WEBPAGE: https://sites.google.com/site/alcardini/home/main
FREE Yellow BOOK on Geometric Morphometrics:
http://www.italian-journal-of-mammalogy.it/issue/view/405
or full volume at:
http://www.italian-journal-of-mammalogy.it/public/journals/3/issue_241_complete_100.pdf
Editorial board for:
Zoomorphology:
http://www.springer.com/life+sciences/animal+sciences/journal/435
Journal of Zoological Systematics and
Evolutionary Research: http://www.wiley.com/bw/journal.asp?ref=0947-5745&site=1
Hystrix, the Italian Journal of
Mammalogy: http://www.italian-journal-of-mammalogy.it/
--
MORPHMET may be accessed via its webpage at http://www.morphometrics.org
---
You received this message because you are subscribed to the Google Groups "MORPHMET" group.
To unsubscribe from this group and stop receiving emails from it, send an email
to morphmet+unsubscr...@morphometrics.org.
