Fifteen diabetic patients were randomly selected, and their blood glucose levels were measured in mg/100 ml with two different devices.
A data frame with 15 observations on the following 3 variables:
patient number
blood glucose level in mg/100 ml using old device
blood glucose level in mg/100 ml using new device
Ugarte, M. D., Militino, A. F., and Arnholt, A. T. (2008) Probability and Statistics with R. Chapman & Hall/CRC.
with(data = glucose, boxplot(Old, New))