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languageR (version 1.0)

lmerPlotInt.fnc: Plot the interaction of two linear numeric predictors in a model fitted with lmer

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.

Examples

Run this code
lexdec.lmer = lmer(RT~BNCw*Frequency+(1|Subject)+(1|Word), data=lexdec)
	lmerPlotInt.fnc(lexdec.lmer, "BNCw", "Frequency", "BNCw:Frequency", which="matplot")

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