PCA Outlier Diagnostics

Calculates Hotelling T^2 (score distance) and Q-residual (orthogonal distance) for each observation, given a chosen number of components.

Usage

pca_outliers(x, X, ncomp, cutoff = FALSE)

Arguments

x

A pca object.

X

The original data matrix used for PCA.

ncomp

Number of components to consider.

cutoff

Logical or numeric specifying threshold for labeling outliers. If TRUE, uses some typical statistical threshold (F-dist) for T^2, or sets an arbitrary Q limit. If numeric, treat it as a cutoff. Default is FALSE (no labeling).

Value

A data frame with columns T2 and Q, and optionally an outlier flag.