ade4 (version 1.7-19)

loocv.dudi: Leave-one-out cross-validation for a dudi

Description

Leave-one-out cross-validation to check the dispersion of row coordinates in a dudi.

Usage

# S3 method for dudi
loocv(x, progress = FALSE, ...)

Value

A list with:- XValCoord: the cross-validated row coordinates - PRESS: the Predicted Residual Error Sum for each row- PRESSTot: the sum of PRESS for each bca axis

Arguments

x

the dudi of the bca on which cross-validation should be done

progress

logical to display a progress bar during computations (see the progress package)

...

further arguments passed to or from other methods

Author

Jean Thioulouse

Details

This function does a cross-validation of the row coordinates of a dudi. Each row is removed from the table one at a time, and its coordinates are computed by projection of this row in the analysis of the table with the removed row. This can be used to check the sensitivity of an analysis to outliers. The cross-validated and original coordinates can be compared with the s.match function (see example).

See Also

loocv.between, loocv.discrimin, suprow, s.match

Examples

data(meaudret)
envpca <- dudi.pca(meaudret$env, scannf = FALSE, nf = 3)
xvpca <- loocv(envpca)
s.match(envpca$li, xvpca$XValCoord)