lmerPlotInt.fnc: Plot the interaction of two linear numeric predictors in a...

In languageR: Analyzing Linguistic Data: A Practical Introduction to Statistics

Description

Visualization of an interaction in a model fitted with lmer of two numeric predictors.

Usage

lmerPlotInt.fnc(lmermodel, xname, yname, intxyname, 
                qntls = seq(0, 1, by = 0.1), view = 30, 
                addStdError = FALSE, ndigits = 2, nlev = 30, 
                which = "matplot", shadow = 0.5, colour = "lightblue", 
                fun  = NA, ylabel = NA, ...)

Arguments

lmermodel	an lmer model object
xname	name (character string) of first numeric predictor
yname	name (character string) of second numeric predictor
intxyname	name (character string) of the interaction in the lmer summary
qntls	vector of values to be shown for the second numeric predictor, defaults to deciles
view	specifies the viewing parameter theta for the perspective plot
addStdError	add noise with the standard deviation of the residual error in the lmer model to the plot
ndigits	number of digits to show for the second numeric predictor
nlev	number of levels for the contour plot
which	choices are "matplot" (default), "contour", "persp", "image", and "all", in which case a 2 by 2 panel is shown with all four plots
shadow	the amount of shade for the perspective plot
colour	the color used for the perspective plot, defaults to "lightblue"
fun	for matplot displays, a function for transforming the predicted response
ylabel	string, to be added to the Y-axis as y label
...	other arguments

Value

A plot is shown on the graphics device.

Warning

This function should not be used to plot interactions when one of the predictors also has quadratic or higher terms in the model.

Author(s)

R. H. Baayen

Examples

  ## Not run: 
  require(lme4)
  require(optimx)
	lexdec.lmer = lmer(RT~BNCw*Frequency+(1|Subject)+(1|Word), data=lexdec,
    control=lmerControl(optimizer="optimx",optCtrl=list(method="nlminb")))
	lmerPlotInt.fnc(lexdec.lmer, "BNCw", "Frequency", "BNCw:Frequency", 
    which="matplot")

## End(Not run)
  

languageR documentation built on May 2, 2019, 10:02 a.m.