outlier_multi: Multivariate outliers In phytomosaic/ecole: ecole: School of Ecology Package

Description

Find extreme values in ecological community data

Usage

 ```1 2``` ```outlier_multi(x, mult = 3, method = "bray", metric = "SD", plot = TRUE, perc = NULL, pick = NULL, ...) ```

Arguments

 `x` array of species data `mult` SD threshold for 'outliers' = the number of SD's away from the mean distance at which an outlier is defined; default is 3 times the SD `method` distance measure; follows `vegdist` `metric` defaults to 'SD'; only other alternative is 'MAD' `plot` logical, should a histogram of distances be drawn? `perc` numeric, returns outlier values beyond the specified percentile `pick` numeric, returns this number of most extreme outliers `...` further arguments passed to other methods

Details

Outlier analysis based on community distances. Emulates PC-ORD, but see also McCune and Grace (2002).

Value

A data frame with plot identifiers, calculated distances, and standard deviations from the mean distance, either with or without a histogram.

References

McCune, B., and J. B. Grace. 2002. Analysis of Ecological Communities. MjM Software, Gleneden Beach, Oregon, USA. 304 pp.

`outlier_uni` for univariate analog.
Other outlier functions: `outlier_uni`
 ```1 2 3 4 5 6 7 8``` ```require(vegan) data(dune) set.seed(19) spe <- rbind(dune, runif(ncol(dune),0,1000)) # add an outlier row outlier_multi(spe, mult=3, plot=FALSE) outlier_multi(spe, mult=3) outlier_multi(spe, perc=5) outlier_multi(spe, pick=5) ```