procrustes_loadings: Generate distribution of (index) loadings using the bootstrap...

In nzilbb.vowels: Vowel Covariation Tools

Generate distribution of (index) loadings using the bootstrap and Procrustes rotation.

Description

Generate distribution of loadings or signed index loadings for Principal Components. These are used in order to estimate confidence intervals for loadings and, if signed index loadings are used, also a null distribution for tests of statistical significance. Plot the results using plot_procrustes_loadings().

Usage

procrustes_loadings(pca_data, max_pcs, index = TRUE, n = 500, scale = TRUE)

Arguments

pca_data	data fed to the prcomp function.
max_pcs	maximum number of PCs to rotate.
index	whether to use signed index loadings rather than loadings (default: TRUE)
n	the number of bootstrapped and permuted samples.
scale	whether the variables in pca_data should be scaled before PCA (default: TRUE)

Value

a tibble, with columns:

• source either "Sampling", "Null" or "Original", identifying where the loadings comes from. "Original" identifies loadings from the full dataset, "Sampling" identifies loadings from the bootstrapped samples, "Null" identifes loadings from permuted versions of the data.

• id identifies which iteration of either permutation or bootstrapping the loading comes from.

• variable indicates the variable corresponding to the loading.

• a column containing the loading for each PC up to max_pcs.

Examples

  proc_loadings <- procrustes_loadings(
    pca_data = onze_intercepts |> dplyr::select(-speaker),
    max_pcs = 3,
    index = TRUE,
    n = 10, # set this to at least 100 in actual use.
    scale = TRUE
   )

nzilbb.vowels documentation built on June 8, 2025, 12:35 p.m.