[R-sig-eco] Mantel correlogram?

[Sarah Goslee]

Hi Kathy,

It's easiest to answer questions like that if you provide enough of
your data to create a reproducible example, like:
dput(head(mydata, 15))

But it sounds like you may just need subset(), rather than this being
a question about Mantel correlograms per se.

A Mantel correlogram is a good choice if your hypothesis is expressed
in terms of distances, rather than in terms of raw data. It can't
magically make up for insufficient data: if you don't have enough data
to calculate a meaningful semivariogram, you also don't have enough to
calculate a meaningful Mantel correlogram.

Sarah

On Tue, Mar 12, 2013 at 7:27 AM, Kathleen Regan <kath.regan at gmail.com> wrote:
> I would like to use the package "ecodist" to compute Mantel correlograms
> for particular variables for each of 6 different time points. Each sample
> at each time point has  unique x and y coordinates on a plot. I have saved
> a test file as a matrix, and can read in R that "x" and "y" as well as my
> variables of interest are all present in the matrix file.
>
> I just don't know how to write the command for a Mantel correlogram for
> (e.g.) Cmic (one variable) for a particular sampling date, as well as Cmic
> for all 6 sampling dates (which, if they could be plotted all on one graph
> would be super.)
>
> The point of this is to see how Cmic (and other variables) changes in both
> space and time over my plot. I will then look at other belowground
> variables and aboveground plant biomass data for each date in the same way.
>
> I'm not even sure Mantel correlograms are the best choice here, but sadly,
> my lag distances for my samples aren't close enough together for me to get
> nice semivariograms. Originally I had hoped to have both conventional stats
> for changes over time coupled with maps to show changes in space at each
> time point. It was suggested to me that Mantel correlograms would be an
> alternative way to visualize spatial variability on my plot.
>
> I apologize in advance for my clumsiness with R. I have read the Legendre
> and Goslee papers, have studied (as best I can) both the books and the
> online info for this package, but since I have no (absolutely NO)
> experience with program languages, the help is often impenetrable to me.
>
> Any and all suggestions most welcome!
>
> Thanks very much -Kathy
>
> --
> Kathleen Regan
>
> University of Hohenheim


-- 
Sarah Goslee
http://www.functionaldiversity.org