The diameter in millimeters for a random sample of 15 diodes from each of the two suppliers is stored in the data frame LEDDIODE.
LEDDIODEA data frame with 30 observations on the following 2 variables:
diameter (diameter of diode measured in millimeters)
supplier (factor with levels supplierA and supplierB)
Ugarte, M. D., Militino, A. F., and Arnholt, A. T. 2015. Probability and Statistics with R, Second Edition. Chapman & Hall / CRC.
ggplot(data = LEDDIODE, aes(supplier, diameter)) + geom_boxplot()