Dear Alyson.

`There is no general rule about this; however, my suggestion would be to`

`use log-scaled values. This is because on a log-scale proportional`

`changes in the trait are equal, independent of the magnitude of the`

`trait. That is, a change of 1% in mass of whale is the same as a change`

`in 1% in mass of a mouse. If your analysis includes both mice and`

`whales, then on the original scale mice may appear to be changing very`

`little in mass, while whales change a great deal - even if (relative to`

`their sizes) both groups are changing just as much. On the other hand,`

`if your analysis is of only whales or only mice it will make relatively`

`little difference whether you use log-scaled data or the original values.`

I hope this is of some help. All the best, Liam Liam J. Revell, Associate Professor of Biology University of Massachusetts Boston web: http://faculty.umb.edu/liam.revell/ On 7/13/2018 2:07 PM, Alyson Brokaw wrote:

Hello Everyone, I am working with a comparative dataset using bat morphometrics. As part of my analysis, I want to estimate the phylogenetic signal of my variables. I understand how to do this using R. My question is more specifically about what kind of data I should be using when calculating the estimates. For the purposes of my other analyses (linear regressions), I have log-transformed my data to meet assumptions for normality. When estimating phylogenetic signal, should I use my non-transformed, raw variables or the transformed variables? I get slightly different outputs if I run both on the same measure. My intuition is that using the raw values is more interpretable, but figured I would ask some people with more experience. Thank you for your time. -Alyson ____________________________________________________________ Alyson Brokaw M.S. Candidate: Biology, Humboldt State University Cornell University '11, Ecology and Evolutionary Biology LinkedIn Profile <http://www.linkedin.com/pub/alyson-brokaw/3a/704/820> Follow my research journey here! <http://afbrokaw.wordpress.com/> [[alternative HTML version deleted]] _______________________________________________ R-sig-phylo mailing list - R-sig-phylo@r-project.org https://stat.ethz.ch/mailman/listinfo/r-sig-phylo Searchable archive at http://www.mail-archive.com/r-sig-phylo@r-project.org/

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