Adding data points to boxplots with stripchart

pre<-55+rnorm(20)
post<-pre+0.7+rnorm(20)

s<-seq(length(pre))
 

par(bty="l")
 

boxplot(pre,post,main="Rawdata",xlab="Time",ylab="Measure",names=c("pre","post"), 

          col=c("lightblue","lightgreen"))
 

stripchart(list(pre,post),vertical=T,pch=16,method="jitter",cex=0.5,add=T)

for more see

surefoss page