Hi all,
I am running an OU model on data that is constrained by zero (precipitation
values). Therefore I thought to log transform the data. However I still
have some issues with the transformation:
1. When all values in the data are larger than 1.0, the log transformation
will still result in
Given the nature of precipitation data, I don't think a log transform makes
sense biologically. It is very different from, say, body mass.
I think you need to simulate with limits, as described originally here:
Garland, T., Jr., A. W. Dickerman, C. M. Janis, and J. A. Jones. 1993.
Phylogenetic
Ted Garland wrote:
Our programs are in DOS (What's DOS? The last operating system
that worked ...).
However, I think you can also do this in R somewhere, maybe
phytools? Liam Revell, want to jump in here?
Just to remind people: DOS (also called MSDOS) executables programs
can be run
Good point, Joe.
However, if they have graphics screens (as in our PDTREE.EXE and PDSIMUL.EXE)
programs, then you sometimes have trouble with the display of those particular
screens. Plain text screens (ASCII characters only) aren't a problem. Also,
you can get idiosyncratic problem, such as
I had been imagining that precipitation was a dependent variable, not that it
matters. In any case, you have the need for a lower limit of zero and probably
an upper limit that is somewhat above the greatest recorded values. I can't
see why you would want an OU model for precipitation,
