Returns a vector of variable numbers corresponding to the model
having lowest prediction error.
Arguments
y
vector of response values (numeric or factor).
X
numeric predictor matrix.
ncomp
integer number of components (default = 10).
ratio
the proportion of the samples to use for calibration (default = 0.75).
VIP.threshold
thresholding to remove non-important variables (default = 1).
Author
Tahir Mehmood, Kristian Hovde Liland, Solve Sæbø.
Details
Variables are first sorted with respect to some importancemeasure,
and usually one of the filter measures described above are used. Secondly, a
threshold is used to eliminate a subset of the least informative variables. Then
a model is fitted again to the remaining variables and performance is measured.
The procedure is repeated until maximum model performance is achieved.
References
I. Frank, Intermediate least squares regression method, Chemometrics and
Intelligent Laboratory Systems 1 (3) (1987) 233-242.