----- Forwarded message from Philipp Mitteröcker <mitte...@univie.ac.at> -----
Date: Thu, 28 Nov 2013 11:26:34 -0500
From: Philipp Mitteröcker <mitte...@univie.ac.at>
Reply-To: Philipp Mitteröcker <mitte...@univie.ac.at>
Subject: Re: missing structures
To: morphmet@morphometrics.org
The problem raised by Patrick is not really a missing data problem.
Missing data, in the technical sense, are structures or properties that do
exist in the specimens but could not have been measured. Hence it can make some
sense to estimate them. But when structures simply do not exist in some
specimens, what does it mean to estimate them?
In other words, if a structure is present in one group and absent in another
group, these groups differ not only quantitatively but also qualitatively.
Estimating the values, or letting landmarks overlap, means that a qualitative
difference is -- arbitrarily -- substituted by a quantitative one. Many
statistical results will be affected by this arbitrariness.
Note also that missing data approaches usually require the data to be missing
at random, which is presumably not the case in the problem at hand.
Best,
Philipp
Am 28.11.2013 um 10:55 schrieb morphmet_modera...@morphometrics.org:
>
> ----- Forwarded message from sebastien couette
> <sebastien.coue...@u-bourgogne.fr> -----
>
> Date: Mon, 25 Nov 2013 05:06:20 -0500
> From: sebastien couette <sebastien.coue...@u-bourgogne.fr>
> Reply-To: sebastien couette <sebastien.coue...@u-bourgogne.fr>
> Subject: Re: missing structures
> To: morphmet@morphometrics.org
>
> Dear Patrick,
>
> I published a paper on missing data in 2010:
>
> Sébastien Couette, Jess White (2010)3D geometric morphometrics and
> missing-data. Can extant taxa give clues for the analysis of fossil
> primates?
> Comptes Rendus Palevol 9(6):423-433. DOI:10.1016/j.crpv.2010.07.002
>
> I can send you a copy.
>
> There is also a good paper on this topic in Systbiol:
>
> Brown, C.M., Arbour, J.H., Jackson,D.A. (2012). testing the effect of
> missing data estimation and distribution in morphometric multivariate
> data analyses. Systematic biology,61(6),941-954.
>
> Feel free to contac me if any questions
>
> Sébastien
>
> --
> -----------------------------------------
> Dr. Sébastien Couette
>
> EPHE&UMR CNRS 6282 Biogéosciences
> Université de Bourgogne
> 6 Bld Gabriel
> 21000 Dijon
>
> Tél.: 33. (0)3.80.39.64.48
> Fax : 33. (0)3.80.39.63.87
>
> sebastien.coue...@u-bourgogne.fr
> http://www.u-bourgogne.fr/BIOGEOSCIENCE/
>
> Responsable de la spécialité "Biodiversité et Gestion de l'Environnement" du
> Master "Biologie Santé Ecologie" de l'EPHE
>
> Master EPHE spécialité "Biodiversité et Gestion de l'Environnement"
> http://biodiv-envt-ephe-prefig.com/
>
> ----- End forwarded message -----
>
>
___________________________________
Dr. Philipp Mitteroecker
Department of Theoretical Biology
University of Vienna
Althanstrasse 14
A-1090 Vienna, Austria
Tel: +43 1 4277 56705
Fax: +43 1 4277 9544
email: philipp.mitteroec...@univie.ac.at
homepage: http://theoretical.univie.ac.at/people/mitteroecker
----- End forwarded message -----
