envelope.student: QQ-plot with simulated envelopes

Description

Constructs a normal QQ-plot using a Wilson-Hilferty transformation for the estimated Mahalanobis distances obtained from the fitting procedure.

Usage

envelope.student(object, reps = 50, conf = 0.95, plot.it = TRUE)

Value

A list with the following components :

transformed: a vector with the z-scores obtained from the Wilson-Hilferty transformation.
envelope: a matrix with two columns corresponding to the values of the lower and upper pointwise confidence envelope.

Arguments

object: an object of class 'studentFit' representing the fitted model.
reps: number of simulated point patterns to be generated when computing the envelopes. The default number is 50.
conf: the confidence level of the envelopes required. The default is to find 95% confidence envelopes.
plot.it: if TRUE it will draw the corresponding plot, if FALSE it will only return the computed values.

References

Atkinson, A.C. (1985). Plots, Transformations and Regression. Oxford University Press, Oxford.

Osorio, F., Galea, M., Henriquez, C., Arellano-Valle, R. (2023). Addressing non-normality in multivariate analysis using the t-distribution. AStA Advances in Statistical Analysis 107, 785-813.

Examples

Run this code

data(PSG)
fit <- studentFit(~ manual + automated, data = PSG, family = Student(eta = 0.25))
envelope.student(fit, reps = 500, conf = 0.95)