Hello Steve, > I've been asked to help evaluate a vegetation data set, specifically to > examine it for community similarity. The initial problem I see is that the > data is ordinal. At best this only captures a relative ranking of > abundance and ordinal ranks are assigned after data collection.
Just about every vegetation survey ever conducted uses either presence absence or ordinal data collection (e.g. Braun-Blanquet scores or importance scores from nested quadrats). A large number of distance metrics are in the literature to deal with such data. As well as Phil's suggestion you should definitely look at the vegan package which contains a good selection of these metrics plus numerous functions frequently used in classification and ordination of veg data. Michael On 20 October 2010 05:14, <steve_fried...@nps.gov> wrote: > > Hello > > I've been asked to help evaluate a vegetation data set, specifically to > examine it for community similarity. The initial problem I see is that the > data is ordinal. At best this only captures a relative ranking of > abundance and ordinal ranks are assigned after data collection. I've > been trying to find a procedure in R that can handle ordinal based > classification and so far have not found one. > > Does one exist ? If there is one, which package supports this type of > analysis and what is the function ? > > Thanks in advance. > Steve > > > > > Steve Friedman Ph. D. > Spatial Statistical Analyst > Everglades and Dry Tortugas National Park > 950 N Krome Ave (3rd Floor) > Homestead, Florida 33034 > > steve_fried...@nps.gov > Office (305) 224 - 4282 > Fax (305) 224 - 4147 > > ______________________________________________ > R-help@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-help > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html > and provide commented, minimal, self-contained, reproducible code. > ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
