ade4 (version 1.5-2)

testdim: Function to perform a test of dimensionality

Description

This functions allow to test for the number of axes in multivariate analysis. The procedure is only implemented for principal component analysis on correlation matrix. The procedure is based on the computation of the RV coefficient.

Usage

testdim(dudi, ...)
## S3 method for class 'pca':
testdim(dudi, nrepet = 99, nbax = dudi$rank, alpha = 0.05, ...)

Arguments

dudi

a duality diagram (an object of class dudi)

nrepet

the number of repetitions for the permutation procedure

nbax

the number of axes to be tested, by default all axes

alpha

the significance level

...

other arguments

Value

• An object of the class krandtest. It contains also:
• nb
  The estimated number of axes to keep
• nb.cor
  The number of axes to keep estimated using a sequential Bonferroni procedure

References

Dray, S. (2007) On the number of principal components: A test of dimensionality based on measurements of similarity between matrices. Computational Statistics and Data Analysis, in press.

See Also

dudi.pca, RV.rtest

Examples

tab <- data.frame(matrix(rnorm(200),20,10))
pca1 <- dudi.pca(tab,scannf=FALSE)
test1 <- testdim(pca1)
test1
test1$nb
test1$nb.cor
data(doubs)
pca2 <- dudi.pca(doubs$env,scannf=FALSE)
test2 <- testdim(pca2)
test2
test2$nb
test2$nb.cor