influence.ME (version 0.9-6)

plot.estex: Dotplot visualization of measures of influence

Description

This is a wrapper function to the dotplot() function in the lattice-package.

Usage

"plot"(x, which="dfbetas", sort=FALSE, to.sort=NA, abs=FALSE, cutoff=0,
						parameters=seq_len(ncol(estex$alt.fixed)), groups=seq_len(nrow(estex$alt.fixed)), ...)

Arguments

x

An object as returned by the influence() function, containing the altered estimates of a mixed effects regression model.

which

Select which measure of influence is to be plotted. Available options are: "dfbetas" to visualize dfbetas, "cook" to plot the cook's distances, "pchange" to plot the percentage change, and "sigtest" to plot the test statistic of a parameter estimate after deletion of specific cases.

sort

If sort=TRUE The values of the selected measure of influence are ordered based on magnitude before visualization. If sort=FALSE (default) no sorting takes place.

to.sort

Specify on which variable the values of the selected measure of influence must be sorted. If only one variable present (either in the model, or due to the selection specified in parameters), this parameter can be omitted. If multiple variables are visualized, and sort=TRUE, specification of to.sort is required, or an error is returned.

abs

If abs=TRUE, the absolute values of the values of the selected measure of influence are visualized, while if abs=FALSE (default), both positive and negative values are possible. If both abs=TRUE and sort=TRUE, the abs parameters precedes the sort parameter, and thus the absolute values of the selected measure of influence are sorted.

cutoff

Values of the selected measure of influence exceeding the specified (cutoff) value are plotted visually different from values not exceeding the cutoff. If cutoff=0 (default), no such differentiation is made in the way values are plotted.

parameters

Used to define a selection of parameters. If left unspecified (default), values for the selected measure of influence are visualized for parameters in the model.

groups

Used to define a selection of nesting groups that should be visualized. If left unspecified (default), the values of the selected measure of influence for all nesting groups are shown.

...

Further arguments passed on to the dotplot() function.

See Also

influence, dfbetas.estex, cooks.distance.estex, pchange, sigtest

Examples

data(school23)
model <- lmer(math ~ structure + SES  + (1 | school.ID), data=school23)

alt.est <- influence(model, "school.ID")
plot(alt.est, which="dfbetas")
plot(alt.est, which="cook", sort=TRUE)