QuantPsyc (version 1.5)

graph.mod: Moderation Graph

Description

x-y plot containing the simple slopes conditioned on z.

Usage

graph.mod(ssmod, x, y, data, title = "", xlab = "Centered X", ylab = "Raw Y", ylimit = 1.5, ...)

Arguments

ssmod

Results of sim.slopes; Simple Slopes to be graphed

x

Explanatory variable to be used in xyplot

y

Outcome variable to be used in xyplot

data

data.frame containing x, z, y

title

Optional 'main' title for the plot

xlab

x-axis label

ylab

y-axis label

ylimit

used as a multiple of SDy to define the limits of the y-axis

...

to be determined ...

Value

A plot object.

Warning

This is based on a simple 3 variable moderation model with continuous variables. Users must modify the functions to accomodate other models (e.g., categorical moderators, covariates)

Details

Given moderate.lm and sim.slopes, this function plots x,y and adds the simple slopes corresponding to arbitrary values of z defined in sim.slopes. Users must 'click' on an area to add the legend.

References

Aiken, L. S., & West, S. G. (1991). Multiple regression: Testing and interpreting interactions. Newbury Park: Sage Publications.

Cohen, J., Cohen, P., West, S. G., & Aiken, L. S. (2003). Applied multiple regression/correlation analysis for the behavioral sciences, 3rd ed. Mahwah, NJ: Lawrence Erlbaum Associates.

See Also

moderate.lm, sim.slopes

Examples

data(tra)
lm.mod1 <- moderate.lm(beliefs, values, attitudes, tra)
ss.mod1 <- sim.slopes(lm.mod1, tra$values)
## requires user interaction 
## graph.mod(ss.mod1,beliefs,attitudes,tra,"Interaction Example")