I agree with Dave here. White noise has two parameters, mean and variance, and
- to me - is an interesting model to test. But I'm not sure it should be
considered as a baseline.
One can link Brownian motion and white noise through the Ornstein-Uhlenbeck
model - BM is OU with alpha (constraint)
I don't find the white noise to be any good evolutionary scenario: it's
nowhere continuous. It just reduces to the assumption of normal,
independent observations at the tips. Nothing fancy, then :)
Cecile.
On 01/31/11 11:53, Luke Harmon wrote:
I agree with Dave here. White noise has two
Hi Joe et al.,
One point for clarification and your further thoughts.
The way parameterize the OU process in Lavin et al. (2008) it is a
value of zero (not infinity) that gives a start phylogeny with
contemporaneous tips. Sometimes the ML estimate of d (what we call
it) goes to zero, but more
Ted said --
One point for clarification and your further thoughts.
The way parameterize the OU process in Lavin et al. (2008) it is a
value of zero (not infinity) that gives a start phylogeny with
contemporaneous tips. Sometimes the ML estimate of d (what we call
it) goes to zero, but more
The link between BM and WN is even closer than that: WN is the
derivative of a BM process. Now, BM is nowhere differentiable, so in the
usual sense, WN doesn't really exist. However, it can be approximated by
simulation.
Cheers,
Simon.
On 01/02/11 03:53, Luke Harmon wrote:
I agree with
Dear Enrico/Emmanuel,
Actually, I just realized I need continuous traits, not discrete. Sorry about
that. Thanks so much for pointing me towards rTrait(using Cont).
Would it be right that a one optima OU model with rTraitCont would have theta
set to one single value? And a two optima model
