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, ...) ## S3 method for class 'default': simpleSlope(object, pred, mod1, mod2="none",coded = "none", ...)
- an object of class "lmres": a moderated regression function.
- name of the predictor variable
- name of the first moderator variable
- name of the second moderator variable. Default "none" is used in order to analyzing two way interaction,
- 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
-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.
## 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, ...) UseMethod("simpleSlope")