Data which show the effect of two soporific drugs (increase in hours of sleep compared to control) on 10 patients.
A data frame with 20 observations on 3 variables.
|[, 1]||extra||numeric||increase in hours of sleep|
|[, 2]||group||factor||drug given|
|[, 3]||ID||factor||patient ID|
group variable name may be misleading about the data:
They represent measurements on 10 persons, not in groups.
Cushny, A. R. and Peebles, A. R. (1905) The action of optical isomers: II hyoscines. The Journal of Physiology 32, 501–510.
Student (1908) The probable error of the mean. Biometrika, 6, 20.
Scheffé, Henry (1959) The Analysis of Variance. New York, NY: Wiley.
require(stats) ## Student's paired t-test with(sleep, t.test(extra[group == 1], extra[group == 2], paired = TRUE)) ## The sleep *prolongations* sleep1 <- with(sleep, extra[group == 2] - extra[group == 1]) summary(sleep1) stripchart(sleep1, method = "stack", xlab = "hours", main = "Sleep prolongation (n = 10)") boxplot(sleep1, horizontal = TRUE, add = TRUE, at = .6, pars = list(boxwex = 0.5, staplewex = 0.25))
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