rrcov (version 0.4-08)

OsloTransect: Oslo Transect Data

Description

The oslo Transect data set contains 360 samples of different plant species collected along a 120 km transect running through the city of Oslo, Norway.

Usage

data(OsloTransect)

source

REIMANN,C., ARNOLDUSSEN,A., BOYD,R., FINNE,T.E., NORDGULEN,Oe., VOLDEN,T. and ENGLMAIER,P. (2006) The Influence of a city on element contents of a terrestrial moss (Hylocomium splendens), The Science of the Total Environment 369 419--432. REIMANN,C., ARNOLDUSSEN,A., BOYD,R., FINNE,T.E., KOLLER,F., NORDGULEN,Oe., and ENGLMAIER,P. (2007) Element contents in leaves of four plant species (birch, mountain ash, fern and spruce) along anthropogenic and geogenic concentration gradients, The Science of the Total Environment 377 416--433. REIMANN,C., ARNOLDUSSEN,A., FINNE,T.E., KOLLER,F., NORDGULEN,Oe., and ENGLMAIER,P., (2007) Element contents in birch leaves, bark and wood under different anthropogenic and geogenic conditions, Applied Geochemistry, 22 1549--1566.

Details

Samples of different plant species were collected along a 120 km transect running through the city of Oslo, Norway (forty samples each of leaves, needles,roots or barks of several plant species), and the concentrations of 25 chemical elements for the sample materials are reported. The factors that influenced the observed element concentrations in the sample materials were investigated. This data set was used in Todorov and Filzmoser (2007) for illustration of the robust statistics for one-way MANOVA implemented in the function Wilks.test.

References

Todorov V. and Filzmoser P. (2007) Robust statistic for the one-way MANOVA, submetted to the Journal of Environmetrics.

Examples

data(OsloTransect)
str(OsloTransect)

##
##  Log-transform the numerical part of the data, 
##  choose the desired groups and variables and 
##  perform the classical Wilks' Lambda test
##
OsloTransect[,14:38] <- log(OsloTransect[,14:38])
grp <- OsloTransect$X.FLITHO
ind <- which(grp =="CAMSED" | grp == "GNEIS_O" |
    grp == "GNEIS_R" | grp=="MAGM")
(cwl <- Wilks.test(X.FLITHO~K+P+Zn+Cu,data=OsloTransect[ind,]))

##
## Perform now the robust MCD based Wilks' Lambda test. 
##  Use the already computed multiplication factor 'xd' and 
##  degrees of freedom 'xq' for the approximate distribution.
##

xd <- -0.003708238
xq <- 11.79073
(mcdwl <- Wilks.test(X.FLITHO~K+P+Zn+Cu,data=OsloTransect[ind,], 
    method="mcd", xd=xd, xq=xq))