mma (version 10.2-2)

moderate: Calculate and plot the direct effect of the selected exposure variable at each level of the moderator.

Description

Calculate and plot the direct effect of the selected exposure variable at each level of the moderator.

Usage

moderate(med1,vari,j=1,kx=1,continuous.resolution=100,plot=T)

Arguments

med1

The med object from the med function.

vari

The name of the moderator.

j

The jth response if the response is multiple.

kx

The moderate effect is with the kx-th predictor(s).

continuous.resolution

The number of equally space points at which to evaluate continuous predictors.

plot

Plot the direct effect at each level of the moderator if ture.

Value

The moderate returns a list where the item result is a data frame with two or three elements

moderator

the moderator levels.

x

the level of the exposure variable -- available only for continuous exposure and moderate with nonlinear method.

de

the direct effect at the corresonding moderator (and exposure) level(s).

Details

Calculate and plot the direct effect of the selected exposure variable at each level of the moderator base on the result from the med function.

See Also

"form.interaction", "test.moderation"

Examples

# NOT RUN {
#nonlinear model
 data("weight_behavior")
 x=weight_behavior[,c(2,4:14)]
 pred=weight_behavior[,3]
 y=weight_behavior[,15]
 data.bin<-data.org(x,y,pred=pred,contmed=c(7:9,11:12),binmed=c(6,10),
     binref=c(1,1),catmed=5,catref=1,predref="M",alpha=0.4,alpha2=0.4)
 temp2<-med(data=data.bin,n=2,nonlinear=TRUE)
 result1=moderate(temp2,vari="race")
 result2=moderate(temp2,vari="age")

#linear model
 data("weight_behavior")
 pred=weight_behavior[,3]
 x=weight_behavior[,c(2,4:14)]
 inter=form.interaction(x,pred,inter.cov=c("race","age"),predref="M") 
 x=cbind(x,inter)
 head(x)
 data.bin<-data.org(x,y,pred=pred,contmed=c(7:9,11:12),binmed=c(6,10),
     binref=c(1,1),catmed=5,catref=1,predref="M",alpha=0.4,alpha2=0.4)
 temp1<-med(data=data.bin,n=2)
 result3=moderate(temp1,vari="race")
 result4=moderate(temp1,vari="age")

##with a transformation of continuous moderator
x=weight_behavior[,c(2,4:14)]
x=cbind(x,age2=x[,"age"]^2)
inter=form.interaction(x,pred,inter.cov=c("age","age2"),predref="M") 
x=cbind(x,inter)
head(x)
data.bin<-data.org(x,y,pred=pred,contmed=c(7:9,11:12),binmed=c(6,10),
                   binref=c(1,1),catmed=5,catref=1,predref="M",alpha=0.4,alpha2=0.4)
temp1<-med(data=data.bin,n=2)
result5=moderate(temp1,vari="age")
# }