Researchers used 7 red and 7 black playing cards to randomly assign 14 volunteer males with high blood pressure to one of two diets for four weeks: a fish oil diet and a standard oil diet. These data are the reductions in diastolic blood pressure.
A data frame with 14 observations on the following 2 variables.
reduction in diastolic blood pressure (in mm of mercury)
factor variable indicating the diet that the subject followed
Ramsey, F.L. and Schafer, D.W. (2002). The Statistical Sleuth: A Course in Methods of Data Analysis (2nd ed), Duxbury.
Knapp, H.R. and FitzGerald, G.A. (1989). The Antihypertensive Effects of Fish Oil, New England Journal of Medicine 320: 1037–1043.