plotSimDiags: Diagnostic plots for simulated data

In DAAG: Data Analysis and Graphics Data and Functions

Diagnostic plots for simulated data

Description

This provides diagnostic plots, closely equivalent to those provided by plot.lm, for simulated data. By default, simulated data are for the fitted model. Alternatively, simulated data can be supplied, making it possible to check the effct of fitting, e.g., an AR1 model.

Usage

plotSimDiags(obj, simvalues = NULL, seed = NULL,
types = NULL, which = c(1:3, 5), layout = c(4, 1), qqline=TRUE,
cook.levels = c(0.5, 1), caption = list("Residuals vs Fitted",
"Normal Q-Q", "Scale-Location", "Cook's distance", "Residuals vs Leverage",
expression("Cook's dist vs Leverage  " * h[ii]/(1 - h[ii]))),
...)

Arguments

obj	Fitted model object - lm or an object inheriting from lm
simvalues	Optional matrix of simulated data.
seed	Random number seed - set this to make results repeatable.
types	If set, this should be a list with six elements, ordinarily with each list element either "p" or c("p","smooth") or (which=2, which=6) NULL or (which=4) "h"
which	Set to be a subset of the numbers 1 to 6, as for plot.lm
layout	Controls the number of simulations and the layout of the plots. For example layout=c(3,4) will give 12 plots in a 3 by 4 layout.
qqline	logical: add line to normal Q-Q plot
cook.levels	Levels of Cook's statistics for which contours are to be plotted.
caption	list: Captions for the six graphs
...	Other parameters to be passed to plotting functions

Details

Diagnotic plots from repeated simulations from the fitted model provide a useful indication of the range of variation in the model diagnistics that are consistent with the fitted model.

Value

A list of lattice graphics objects is returned, one for each value of which. List elements for which a graphics object is not returned are set to NULL. Or if which is of length 1, a lattice graphics object.

residVSfitted	Residuals vs fitted
normalQQ	Normal quantile-quantile plot
scaleVSloc	Scale versus location
CookDist	Cook's distance vs observation number
residVSlev	Standardized residuals (for GLMs, standardized Pearson residuals) vs leverage
CookVSlev	Cook's distance vs leverage

For the default which=c(1:3,5), list items 1, 2, 3 and 5 above contain graphics objects, with list elements 4 and 6 set to NULL.

Note

The graphics objects contained in individual list elements can be extracted for printing, or updating and printing, as required. If the value is returned to the command line, list elements that are not NULL will be printed in turn.

Author(s)

John Maindonald, with some code chunks adapted from plot.lm

References

See plot.lm

See Also

plot.lm, lmdiags

Examples

women.lm <- lm(height ~ weight, data=women)
gphlist <- plotSimDiags(obj=women.lm, which=c(1:3,5))

DAAG documentation built on May 29, 2024, 9:13 a.m.