The data comes from a beer testing experiment where assessors had to rate the bitterness of five beers.
A matrix with 12 rows corresponding to the assessors, 5 columns corresponding to the five periods.
The possible values for the ratings lie in the interval [0, 12]. Note that the data were reordered after the experiment.
Kunert, J. (1998): Sensory experiments as crossover studies. Food Quality and Preference 9, 243-253 (table 1).