ANOVA Test

Blackmore <- Blackmore %>%
   mutate(ageGroup = case_when(age >= 8 & age <= 10 ~ "Youth",
                                                      age > 10 & age <= 12 ~ "Pre-Teen",
                                                      age > 12 & age <= 14 ~ "Early-Teen",
                                                      age > 14 & age <= 18 ~ "Late-Teen"),
                ageGroup = factor(ageGroup, levels=c("Youth", "Pre-Teen", "Early-Teen", "Late-Teen"), ordered=TRUE))

myaov <- aov(exercise ~ group+ageGroup+group:ageGroup, data = Blackmore)

Diagnostic Plots

par(mfrow = c(1,2))
plot(myaov, which=1:2)