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_Friedman at nps.gov Office (305) 224 - 4282 Fax (305) 224 - 4147
Steve -
Take a look at daisy() in the cluster package.
- Phil Spector
Statistical Computing Facility
Department of Statistics
UC Berkeley
spector at stat.berkeley.edu
On Tue, 19 Oct 2010, Steve_Friedman at 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_Friedman at nps.gov
> Office (305) 224 - 4282
> Fax (305) 224 - 4147
>
> ______________________________________________
> R-help at 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.
>
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_Friedman at 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_Friedman at nps.gov > Office (305) 224 - 4282 > Fax ? ? (305) 224 - 4147 > > ______________________________________________ > R-help at 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. >