Re: [MORPHMET] using regression residuals for other analyses

2016-03-24 Thread Joe Felsenstein
These complicated issues aside, there is a simpler reason not to use a residual from a regression as the basis for further analyses. If two characters are under natural selection based on some combination -- such as selection on a ratio between them -- then the current value of character Y is a

Re: [MORPHMET] using regression residuals for other analyses

2016-03-24 Thread Ian Dworkin
Just as a quick follow up (and clarifications). I recognize that there are already a number of methods to deal with these well known issues (McCoy et al. 2006, Klingenberg 1996, Burnaby 1966, etc..) and they may be better ways still. However, since the "using residuals from a pooled

Re: [MORPHMET] using regression residuals for other analyses

2016-03-24 Thread Ian Dworkin
Dean and Andrea, I wanted to follow up on what Dean wrote regarding using residuals from a pooled within-group regression, and what I think may be important discussion that follows from it. Considerable research has gone into investigating this issue, and as Dean points out, most of the time it

RE: [MORPHMET] using regression residuals for other analyses

2016-03-24 Thread Adams, Dean [EEOBS]
Hi Andrea, It is generally preferable to perform the more complex analysis with size included as a covariate. Using a sequential approach that first obtains the shape residuals and then examines patterns using these as data is not guaranteed to get to the same, or even the correct, place.

[MORPHMET] using regression residuals for other analyses

2016-03-24 Thread andrea cardini
Dear All, this is something that, I believe, has already come up in the past. However, I'd like to check it again. What are the issues with, say, regressing shape on size, saving residuals and using those in further analyses (e.g., other regressions or testing group differences etc.)? I

[MORPHMET] II Iberian Symposium on Geometric Morphometrics, Madrid, June 9-10.

2016-03-24 Thread soledad.esteban
Dear colleagues, We are happy to announce that the deadline for abstract submission for the II ISGM has been extended to March 31st: http://2isgm.transmittingscience.org/abstract-information/ Plenary speakers: Benedikt Hallgrimsson (University of Calgary, Canadá), Chris Klingenberg