R: Normal plot with simulated envelope of the residuals.

envelope.pgam {pgam}

R Documentation

Normal plot with simulated envelope of the residuals.

Description

A normal plot with simulated envelope of the residual is produced.

Usage

## S3 method for class 'pgam'
envelope(object, type = "deviance", size = 0.95, 
rep = 19, optim.method = NULL, epsilon = 0.001, maxit = 100, 
plot = TRUE, title="Simulated Envelope of Residuals", verbose = FALSE, ...)

Arguments

`object`	object of class `pgam` holding the fitted model
`type`	type of residuals to be extracted. Default is `deviance`. Options are described in `residuals.pgam`
`size`	value giving the size of the envelope. Default is `.95` which is equivalent to a 95% band
`rep`	number of replications for envelope construction. Default is `19`

, that is the smallest 95% band that can be build

`optim.method`	optimization method to be passed to `pgam` and therefore to `optim`
`epsilon`	convergence control to be passed to `pgam`
`maxit`	convergence control to be passed to `pgam`
`plot`	if `TRUE` a plot of the envelope is produced
`title`	title for the plot
`verbose`	if `TRUE` a sort of information is printed during the running time
`...`	further arguments to `plot` function

Details

Method for the generic function envelope.

Sometimes the usual Q-Q plot shows an unsatisfactory pattern of the residuals of a model fitted and we are led to think that the model is badly specificated. The normal plot with simulated envelope indicates that under the distribution of the response variable the model is OK if only a few points fall off the envelope.

If object is of class pgam the envelope is estimated and optionally plotted, else if is of class envelope then it is only plotted.

Value

An object of class envelope holding the information needed to plot the envelope.

Author(s)

Washington Leite Junger wjunger@ims.uerj.br and Antonio Ponce de Leon ponce@ims.uerj.br

References

Atkinson, A. C. (1985) Plots, transformations and regression : an introduction to graphical methods of diagnostic regression analysis. Oxford Science Publications, Oxford.