perimental Research on Evolution
http://nere.bio.uci.edu/
(A University of California Multicampus Research Project)
Original message
Date: Fri, 8 May 2009 09:09:04 -0700
From: Joe Felsenstein
Subject: Re: [R-sig-phylo] PICs: Why force linear
regressions through the origin
perimental Research on Evolution
http://nere.bio.uci.edu/
(A University of California Multicampus Research Project)
Original message
Date: Fri, 8 May 2009 09:09:04 -0700
From: Joe Felsenstein
Subject: Re: [R-sig-phylo] PICs: Why force linear
regressions through
Gernot Huber asked --
> 1. Why do you have to force a linear regression through the origin
> when using phylogenetically independent contrasts (PICs)?
Because their expectations are zero. A contrast could be either
X1 - X2 or X2 - X1, for one thing. The expectations of X1 and X2
are identica
Hi,
I haven't been able to find answers to the following questions:
1. Why do you have to force a linear regression through the origin
when using phylogenetically independent contrasts (PICs)?
2. If you suspect an inverse linear relationship, would you transform
one axis so you could still
