Arrests data: Effects plots

##Load the data year is numeric, but we want to treat it as a factor

data(Arrests, package = "carData")
Arrests$year <- as.factor(Arrests$year)

Main effects model, with two interactions

arrests.mod <- glm(released ~ employed + citizen + checks +
                   colour*year + colour*age,
                   family=binomial, data=Arrests)

Anova(arrests.mod)

## Analysis of Deviance Table (Type II tests)
## 
## Response: released
##             LR Chisq Df Pr(>Chisq)    
## employed        72.7  1    < 2e-16 ***
## citizen         25.8  1    3.8e-07 ***
## checks         205.2  1    < 2e-16 ***
## colour          19.6  1    9.7e-06 ***
## year             6.1  5    0.29785    
## age              0.5  1    0.49827    
## colour:year     21.7  5    0.00059 ***
## colour:age      13.9  1    0.00019 ***
## ---
## Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

plot all effects

arrests.effects <- allEffects(arrests.mod, 
                              xlevels=list(age=seq(15,45,5)))
plot(arrests.effects, 
     ylab="Probability(released)")

Plot 3-way effect (not in model)

plot(effect("colour:year:age", arrests.mod, 
            xlevels=list(age=15:45)),
     multiline=TRUE, 
     ylab="Probability(released)", 
     rug=FALSE)

colour x year interaction

plot(effect("colour:year", arrests.mod),
      multiline=TRUE, ylab="Probability(released)")

colour x age interaction

plot(effect("colour:age", arrests.mod),
      multiline=FALSE, ylab="Probability(released)")