Simple slopes analysis for Moderated regression
Simple slope analysis according to Cohen, Cohen, West, & Aiken (2003); Bauer & Curran, (2005); and Dawson and Richter (2006) approaches.
simpleSlope(object, pred, mod1, mod2, coded, ...) ## Default S3 method: simpleSlope(object, pred, mod1, mod2="none",coded = "none", ...)
object |
an object of class "lmres": a moderated regression function. |
pred |
name of the predictor variable |
mod1 |
name of the first moderator variable |
mod2 |
name of the second moderator variable. Default "none" is used in order to analyzing two way interaction, |
coded |
a character vector of coded variables |
... |
Simple slope analysis for moderated regression. If two way interaction is analyzed, the function computes simple slope analysis and region of significance( Bauer & Curran, 2005). If three way interaction is analyzed, the function compute simple slope analysis and difference slope test (Dawson and Richter, 2006).
simpleSlope returns an object of class "simpleSlope".
An object of class "simpleSlope" is a list containing at least the following components:
nomY |
the name of dependent variable |
orde |
it's 2 for two way interaction, it's 3 for three way interaction |
points |
Estimated points of dependent variable as a function of levels of moderators and predictor |
simple_slope |
a matrix summarizing simple slopes results |
delta_slope |
(only for three way interaction)a matrix summarizing difference slope tests |
Df |
degree of freedom |
conf95 |
(only for two way interaction)confidence interval of moderator region of significance |
Alberto Mirisola and Luciano Seta
-Bauer, D. J., & Curran, P. J. (2005). Probing Interactions in Fixed and Multilevel Regression: Inferential and Graphical Techniques. Multivariate Behavioral Research, 40(3), 373-400. -Cohen, J., Cohen, P.,West, S. G.,& Aiken, L. S. (2003). Applied multiple regression/correlation analyses for the behavioral sciences (3rd ed.). Mahwah, NJ: Lawerence Erlbaum Associates, Inc. - Dawson, J. F., and Richter, W. (2006) Probing Three-Way interactions in moderated multiple regression: Development and application of a slope difference test. Journal of Applied Psychology, 4, 917-926.
“summary.simpleSlope”
## simple slope for three way interaction
library(car)
data(Highway1)
model3<-lmres(rate~len*trks*sigs1, centered=c("len","trks","sigs1"),data=Highway1)
S_slopes<-simpleSlope(model3,pred="len",mod1="trks", mod2="sigs1")
## The function is currently defined as
function (object, pred, mod1, mod2, coded, ...)
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