[MORPHMET] Article link

[Collyer, Michael]

Here is a direct link for the article Dean mentioned.

 http://onlinelibrary.wiley.com/doi/10./evo.12596/pdf


Michael Collyer

Assistant Professor
Department of Biology
Western Kentucky University
1906 College Heights Blvd. #11080
Bowling Green, KY 42101-1080
Phone: 270-745-8765; Fax: 270-745-6856
Email: michael.coll...@wku.edu

On Jan 13, 2015, at 3:09 PM, Adams, Dean [EEOBS] 
mailto:dcad...@iastate.edu>> wrote:

Colleagues,

I want to alert your attention to a new article on-line at Evolution (Adams and 
Collyer 2015: doi:10./evo.12596). In it we compare two approaches for 
performing phylogenetic regression of high-dimensional shape data (one based on 
PICs and another based on PGLS). We show that although the two methods produce 
the same test statistics, the permutation procedures commonly employed with the 
methods can produce largely divergent statistical results.  We demonstrate that 
randomization tests using PICs have unacceptably high type I error rates, and 
can lead to incorrect statistical and biological inferences. We then discuss 
the statistical reasons for this, explain why the permutation method 
implemented in the PGLS-based procedure leads to correct statistical and 
biological inferences, and explain how the permutation procedure for PICs can 
be adjusted to provide appropriate results.

Best,

Dean

Dr. Dean C. Adams
Professor
Department of Ecology, Evolution, and Organismal Biology
   Department of Statistics
Iowa State University
www.public.iastate.edu/~dcadams/
phone: 515-294-3834


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[MORPHMET] New paper: phylogenetic comparative analysis of shape; different permutation methods provide contrasting results

[Adams, Dean [EEOBS]]

Colleagues,

I want to alert your attention to a new article on-line at Evolution (Adams and 
Collyer 2015: doi:10./evo.12596). In it we compare two approaches for 
performing phylogenetic regression of high-dimensional shape data (one based on 
PICs and another based on PGLS). We show that although the two methods produce 
the same test statistics, the permutation procedures commonly employed with the 
methods can produce largely divergent statistical results.  We demonstrate that 
randomization tests using PICs have unacceptably high type I error rates, and 
can lead to incorrect statistical and biological inferences. We then discuss 
the statistical reasons for this, explain why the permutation method 
implemented in the PGLS-based procedure leads to correct statistical and 
biological inferences, and explain how the permutation procedure for PICs can 
be adjusted to provide appropriate results.

Best,

Dean

Dr. Dean C. Adams
Professor
Department of Ecology, Evolution, and Organismal Biology
   Department of Statistics
Iowa State University
www.public.iastate.edu/~dcadams/
phone: 515-294-3834

-- 
MORPHMET may be accessed via its webpage at http://www.morphometrics.org

To unsubscribe from this group and stop receiving emails from it, send an email 
to morphmet+unsubscr...@morphometrics.org.