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Mantel correlogram?
2 messages · Kathleen Regan, 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