Do Some Statistics and Add to Plot

# do mean and SD *2
total_cup <- c(diameter1, diameter1a, ...)
meanc <- mean(total_cup)
medianc <- median(total_cup)
SD <- sqrt(var(total_cup))
SD2 <- SD * 2
meanplus <- meanc + SD2
meanminus <- meanc - SD2

# add to plot
ylmean<-meanc + 0.003
text(0.2,ylmean,"Mean", srt=0, crt=0)
points(c(0:41),rep(meanc,42),type="l", lty = 1)

ylmedian<-medianc - 0.003
text(0.4,ylmedian,"Median", srt=0, crt=0)
points(c(0:41),rep(medianc,42),type="l", lty = 1)

ylup <- meanplus + 0.004
Text(1.3,ylup,"Mean Plus 2SD", srt=0, crt=0)
points(c(0:41),rep(meanplus,42),type="l", lty = 1)

yldn <- meanminus + 0.004
text(1.5,yldn,"Mean Minus 2SD", srt=0, crt=0)
points(c(0:41),rep(meanminus,42),type="l", lty = 1)

Transcript

And we can add some more statistics to it.  So, we can have a mean, twice the standard deviation - so add lines to indicate that. We put those into the plot. We add our labels to it.